Corporate and group information

1.	*Corporate and group information*

ChipMOS TECHNOLOGIES INC. (the “Company” or “ChipMOS Taiwan”) was incorporated in the Republic of China (“ROC”) on July 28, 1997. The Company and its subsidiaries (collectively referred herein as the “Group”) are primarily engaged in the research, development, manufacturing and sale of high-integration and high-precision integrated circuits and related assembly and testing services. On April 11, 2014, the Company’s shares were listed on the Taiwan Stock Exchange (“TWSE”). On November 1, 2016, the Company’s American Depositary Shares (“ADSs”) was listed on the NASDAQ Global Select Market and traded under the ticker symbol “IMOS”.

On June 17, 2015, the former 47.54%-owned subsidiary, ThaiLin Semiconductor Corp. (“ThaiLin”) was merged with and into ChipMOS Taiwan, with ChipMOS Taiwan being the surviving company after the merger. The transaction was treated as an equity transaction. Please see note 28 for detailed information.

As of October 31, 2016, the former parent company, ChipMOS TECHNOLOGIES (Bermuda) LTD. (“ChipMOS Bermuda”) owned 60.25% of ChipMOS Taiwan’s outstanding shares, was merged with and into ChipMOS Taiwan, with the latter being the surviving company after the merger, pursuant to the agreement and plan of merger, dated January 21, 2016, by and between ChipMOS Bermuda and ChipMOS Taiwan (the “Merger”). Detailed information about the capital reorganization is provided in Note 2 ee).

As of November 30, 2016, the Board of Directors of the Company approved an agreement to form a joint-venture between the Company and Tsinghua Unigroup Ltd. (“Tsinghua Unigroup”). Under the joint-venture agreement, ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”), a wholly-owned subsidiary of ChipMOS Taiwan, will sell 54.98% of the equity interests of its wholly-owned subsidiary, ChipMOS TECHNOLOGIES (Shanghai) LTD. (“ChipMOS Shanghai”), to a group led by Tsinghua Unigroup (“strategic investors”). After the consummation of such equity interest transfer, ChipMOS BVI will own 45.02% of the equity interests of ChipMOS Shanghai. As of December 31, 2016, the assets, liabilities and equity related to ChipMOS Shanghai have been reclassified as held for sale and presented as discontinued operations for satisfying the definition of discontinued operations. The equity transfer was completed in March 2017. Please see Note 18 for detailed information.

Basis of preparation of financial statements and principal accounting policies

12 Months Ended

Dec. 31, 2017

Basis of preparation of financial statements and principal accounting policies

2.	*Basis of preparation of financial statements and principal accounting policies*

Basis of preparation

These consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (“IFRSs”), which collective term includes all applicable individual IFRSs, International Accounting Standards (“IASs”) issued by the International Accounting Standards Board (“IASB”) and Interpretations issued by the International Financial Reporting Interpretations Committee (“IFRIC”) of the IASB.

The consolidated financial statements have been prepared on a historical cost basis, except for the defined benefit pension plans – plan assets measured at fair value.

These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency.

New and amended standards adopted by the group

Amendments to IAS 7 “Disclosure Initiative”

This amendment requires that an entity shall provide more disclosures related to changes in liabilities arising from financing activities, including both changes arising from cash flows and non-cash changes. Please refer to Note 30.

New and revised International Financial Reporting Standards not yet adopted

Amendments to IFRSs which have been published but are not mandatory for the financial year ending December 31, 2017 are not expected to have a material impact on the Group. Major Amendment to IFRSs that are not yet effective are listed below:


New Standards, Interpretations and Amendments	Effective date by IASB
IFRS 9, “Financial Instruments”		January 1, 2018
IFRS 15, “Revenue from Contracts with Customers”		January 1, 2018
IFRS 16, “Leases”		January 1, 2019

When adopting the new standards effective from 2018, the Group will apply the new rules under IFRS 9 “Financial Instruments” (“IFRS 9”) and adopt IFRS 15 “Revenue from Contracts with Customers” (“IFRS 15”) using the modified retrospective approach from January 1, 2018. The significant effects of applying the new standards as of January 1, 2018 are summarized below:

(a)

Financial assets at fair value through other comprehensive income

In accordance with IFRS 9, an entity at its sole option may irrevocably designate an investment in an equity instrument not held for dealing or trading purpose at initial recognition as financial assets at fair value through other comprehensive income. The Group expects to reclassify available-for-sale financial assets, which were stated at cost less any impairment losses, in the amount of NT$9,950 thousand (US$336 thousand), to financial assets at fair value through other comprehensive income. Accordingly, as of January 1, 2018, financial assets at fair value through other comprehensive income, retained earnings and other reserve will be increased by NT$89,335 thousand (US$3,014 thousand), NT$28,584 thousand (US$964 thousand) and NT$50,801 thousand (US$1,714 thousand), respectively.

(b)

Financial assets at fair value through profit or loss

In accordance with IFRS 9, the Group expects to reclassify available-for-sale financial assets, which were stated at cost less any impairment losses, in the amounts of NT$10,940 thousand (US$369 thousand), to financial assets at fair value through profit or loss. Accordingly, as of January 1, 2018, financial assets at fair value through profit or loss and retained earnings will be increased by NT$11,433 thousand (US$386 thousand) and NT$493 thousand (US$17 thousand), respectively.

(c)

Provision for impairment

In line with the regulations under IFRS 9 on provision for impairment based on the expected credit loss model, as of January 1, 2018, contract assets will be decreased by NT$115 thousand (US$4 thousand), accounts receivable decreased by NT$1,819 thousand (US$61 thousand), other receivables decreased by NT$5 thousand (US$169), other receivables – related parties decreased by NT$2 thousand (US$67), and retained earnings decreased by NT$1,941 thousand (US$65 thousand).

(d)

Revenue recognition of customized products

The Group provides high-integration and high-precision integrated circuits and related assembly and testing services based on the specifications as required by the customers. The revenue is recognized when the significant risks and rewards are transferred under existing accounting policies (refer to Note 2 u)), and the timing of recognition usually occurred upon service completion. Considering that the Group provides assembly and testing service to create or enhance a highly customized product and the customer controls the asset as it is created or enhanced, the revenue will be recognized over time based on the percentage of completion under IFRS 15. As of January 1, 2018, using the modified retrospective approach, the Group also elects the use of practical expedient to only account for incomplete contracts at the date of initial application. Hence all the work in process and finished goods accounted in inventories will be transferred to retained earnings and contract assets will be recognized. As a result, retained earnings will be increased by NT$46,607 thousand (US$1,572 thousand), inventory decreased by NT$208,505 thousand (US$7,035 thousand) and contract assets increased by NT$255,112 thousand (US$8,607 thousand).

(e)

Presentation of contract assets and contract liabilities

In line with IFRS 15 requirements, the Group’s liabilities in relation to sales discounts to customers are recognized as contract liabilities, but were previously presented as current provisions on the consolidated statement of financial position. As of January 1, 2018, the balance is NT$70,156 thousand (US$2,367 thousand).

(f)

Recognition of deferred tax

When initially adopting IFRS 9 and IFRS 15, the Group will have to recognize adjustments on the consolidated statement of financial position which would result to temporary differences. Accordingly, as of January 1, 2018, deferred tax assets will be decreased by NT$736 thousand (US$25 thousand) and deferred tax liabilities increased by NT$19,651 thousand (US$663 thousand).

Other Amendments to IFRSs not listed above are not expected to have a material impact on the entity in the current or future reporting periods and on foreseeable future transactions.

Basis of consolidation

The consolidated financial statements include the accounts of ChipMOS Taiwan and all entities controlled by ChipMOS Taiwan. The financial statements of subsidiaries are prepared for the same reporting period as the Company, using consistent accounting policies. The results of subsidiaries are consolidated from the date on which the Group obtains control, and continue to be consolidated until the date that such control ceases.

Profit or loss and each component of other comprehensive income are attributed to the owners of the parent of the Group and to the non-controlling interests, even if this results in the non-controlling interests having a deficit balance. All intra-group transactions, balances, income and expenses are eliminated in full on consolidation.

The Group reassesses whether or not it controls an investee if facts and circumstances indicate that there are changes to one or more of the three elements of control described in the accounting policy for subsidiaries below.

Changes in the Group’s ownership interests in subsidiaries that do not result in the Group losing control over the subsidiaries are accounted for as equity transactions. The carrying amounts of the Group’s interests and the non-controlling interests are adjusted to reflect the changes in their relative interests in the subsidiaries. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity and attributed to owners of the Company.

When the Group loses control of a subsidiary, the profit or loss on disposal is calculated as the difference between (i) the aggregate of the fair value of the consideration received and the fair value of any investment retained and (ii) the previous carrying amount of the assets (including goodwill), and liabilities of the subsidiary and any non-controlling interests. The Group’s share of components previously recognized in other comprehensive income is reclassified to consolidated statements of comprehensive income or retained profits, as appropriate, on the same basis as would be required if the Group had directly disposed of the related assets or liabilities.

Subsidiaries included in the consolidated financial statements:

Percentage of
Ownership (%)

December 31,

Name of investor

Name of investee

Main businesses

Location

2016

2017

Note

The Company

ChipMOS U.S.A., Inc. (“ChipMOS USA”)

Research, development and marketing of semiconductors, circuits, and electronic related products

San Jose, USA

100

The Company

ChipMOS BVI

Holding company

British Virgin Islands

100

ChipMOS BVI

ChipMOS Shanghai

Semiconductor assembling and testing services

People’s Republic of China (“PRC”)

100

—

On November 30, 2016, the Company’s Board of Directors approved ChipMOS BVI’s disposal of 54.98% shareholding of its subsidiary, ChipMOS Shanghai. The transaction was completed in March 2017, thereafter, ChipMOS Shanghai was excluded from the consolidated financial statements and recorded as “Investment in associates”. Detailed information is provided in Note 13.

Significant judgments and estimates

The preparation of consolidated financial statements requires management to make judgments, estimates and assumptions that affect the recorded amounts of assets, liabilities, revenue and expenses of the Group. The Group continually evaluates these estimates, including those related to share-based payments, impairment of receivables, impairment of non-financial assets, depreciation of property, plant and equipment, defined benefit plans, deferred tax assets and deferred tax liabilities. The Group bases its estimates on historical experience and other assumptions, which it believes to be reasonable under the circumstances. Actual results may differ from these estimates under different assumptions and conditions.

The estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimate is revised if the revision affects only that periods, or in the period of the revision and future periods if the revision affects both current and future periods.

Management has considered the development, selection and disclosure of the Group’s critical accounting policies and estimates.

Judgments

In the process of applying the Group’s accounting policies, management has made the following judgments which have the most significant effect on the amounts recognized in the consolidated financial statements:

Provisions – deficiency compensation

The Group is primarily providing high-integration and high-precision integrated circuit of the packaging and testing services. In cases of deficiencies in the assembly and testing services provided, the Group has to clarify the reason for deficiencies and attribution of responsibility. The Group follows the guidance of IAS 37 “Provisions, Contingent Liabilities and Contingent Assets” to determine provisions for deficiency compensation. Since the timing and amount of these provisions are based on assumptions and estimates it requires management to make critical judgments.

Estimates and assumptions

Revenue recognition

The Group estimates sales discounts and returns based on historical results and other known factors. Provisions for such liabilities are recorded as a deduction item to sales revenues when the sales are recognized. The Group reassesses the reasonableness of estimates of discounts and returns periodically.

Causes and effects of accounting change

By considering the Group’s experience on using similar property, plant and equipment in prior periods as well as by referring to the experience from peer industry, on November 10, 2016, the Board of Directors approved to change the estimated useful lives of certain properties from 11 years to 16 years and certain equipment from 2~6 years to 2~8 years effectively from November 1, 2016, in order to better reflect economic benefits from usage of those properties and equipment. The impact on depreciation expenses of current and future periods were expected as follows:


	2016			2017			2018			2019
	NT$000			NT$000			NT$000			NT$000
Decrease in depreciation expenses		(119,737	)		(605,259	)		(389,972	)		(164,824	)

Property, plant and equipment and depreciation

Property, plant and equipment are stated at cost, less provision for depreciation and impairment losses, if any.

The cost of an item of property, plant and equipment comprises its purchase price and any directly attributable cost of bringing the asset to its working condition and location for its intended use. Expenditure incurred after the item has been put into operation, such as repairs and maintenance and overhaul costs, is normally charged to the consolidated statements of comprehensive income in the year in which it is incurred. In situations where it can be clearly demonstrated that the expenditure has resulted in an increase in future economic benefits expected to be obtained from the use of the item, the expenditure is capitalized as an additional cost of the item. When an item of property, plant and equipment is disposed of or retired, its cost and accumulated depreciation are removed from the financial statements and any gain or loss resulting from the disposal or retirement, being the difference between the net proceeds and the carrying amount of the asset, is included in consolidated statements of comprehensive income.

Depreciation is provided on the straight-line method, based on the estimated useful life of the individual assets, as follows:


Buildings		6 to 51 years
Machinery and equipment		2 to 8 years
Tools		2 to 3 years
Other equipment		2 to 6 years

Where parts of an item of property, plant and equipment have different useful lives, the cost of that item is allocated on a reasonable basis among the parts and each part is depreciated separately. Residual values, useful lives and the depreciation method are reviewed, and adjusted if appropriate, at least at each financial year end.

An item of property, plant and equipment including any significant part initially recognized is derecognized upon disposal or when no future economic benefits are expected from its use or disposal. Any gain or loss on disposal or retirement recognized in the consolidated statements of comprehensive income in the year the asset is derecognized is the difference between the net sales proceeds and the carrying amount of the relevant asset.

Impairment of non-financial assets

Where an indication of impairment exists, or when periodical impairment testing for an asset is required (other than inventories, deferred tax assets and financial assets), the recoverable amount of the asset is estimated. An asset’s recoverable amount is the higher of the value in use of the asset or cash-generating unit to which it belongs and its fair value less costs to sell, and is determined for an individual asset, unless the asset does not generate cash inflows that are largely independent of those from other assets or groups of assets, in which case the recoverable amount is determined for the cash-generating unit to which the asset belongs.

An impairment loss is recognized only if the carrying amount of an asset exceeds its recoverable amount. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset. An impairment loss is charged to the consolidated statements of comprehensive income in the period in which it arises in those expense categories consistent with the function of the impaired asset.

An assessment is made at the end of each reporting period as to whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such indication exists, the recoverable amount is estimated. A previously recognized impairment loss of an asset is reversed only if there has been a change in the estimates used to determine the recoverable amount of that asset, but not to an amount higher than the carrying amount that would have been determined (net of any depreciation), had no impairment loss been recognized for the asset in prior years. A reversal of such impairment loss is credited to the consolidated statements of comprehensive income in the period in which it arises.

Inventories

Inventories are stated at the lower of cost and net realizable value. Cost is determined on a weighted average cost basis and includes all costs of purchase, costs of conversion, and other costs incurred in bringing the inventories to their present location and condition.

Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale.

When inventories are consumed, the carrying amount of those inventories is recognized as cost of revenue in the period in which the related revenue is recognized. The amount of any write-down of inventories to net realizable value and all losses of inventories are recognized as cost of revenue in the period the write-down or loss occurs. The amount of any reversal of any write-down of inventories is recognized as a reduction in the amount of inventories recognized as cost of revenue in the period in which the reversal occurs.

Non-current assets held for sale

Non-current assets are classified as assets held for sale when their carrying amount is to be recovered principally through a sale transaction rather than through continuing use, and a sale is considered highly probable. They are stated at the lower of carrying amount and fair value less costs to sell.

Investments and other financial assets

Initial recognition and measurement

The Group’s financial assets are classified, at initial recognition, into financial assets at fair value through profit or loss (“FVTPL”), loans and receivables and available-for-sale financial investments. When financial assets are recognized initially, they are measured at fair value plus transaction costs that are attributable to the acquisition of the financial assets.

All regular way purchases or sales of financial assets are recognized on the settlement date, that is, the date that the Group completes the purchase or sell of the asset. Regular way purchases or sales are purchases or sales of financial assets that require delivery of assets within the time frame established by regulation or convention in the marketplace.

Effective interest method

The effective interest method is a method of calculating the amortized cost of loans and receivables and a debt instrument and of allocating interest income over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash receipts (including all fees on points paid or received that form an integral part of the effective interest rate, transaction costs and other premiums or discounts) through the expected life of the debt instrument, or, where appropriate, a shorter period.

Income is recognized on an effective interest basis for debt instruments.

Subsequent measurement

The subsequent measurement of financial assets depends on their classification as follows:

Financial assets at fair value through profit or loss

Financial assets at FVTPL include financial assets held for trading and those designated as at FVTPL upon initial recognition.

A financial asset is classified as held for trading, mainly for cash management purpose as part of operating activities, if it has been acquired principally for the purpose of selling in the near future; or it is a part of an identified portfolio of financial instruments that the Group manages together and has a recent actual pattern of short-term profit-taking; or it is a derivative that is not designated and effective as a hedging instrument.

A financial asset other than a financial asset held for trading may be designated as at FVTPL upon initial recognition if:

•

such designation eliminates or significantly reduces a measurement or recognition inconsistency that would otherwise arise; or

•

the financial asset forms part of a group of financial assets or financial liabilities or both, which is managed and its performance is evaluated on fair value basis, in accordance with the Group’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or

•

it forms part of a contract containing one or more embedded derivatives, and IAS 39 “Financial Instruments: Recognition and Measurement” permits the entire combined contract (asset or liability) to be designated as at FVTPL.

There were no financial assets at FVTPL at the end of the reporting periods.

Loans and receivables

Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted in an active market. At the end of each reporting period, subsequent to initial recognition, loans and receivables (including accounts and notes receivables, other receivables, refundable deposits, short-term deposits and cash and cash equivalents) are carried at amortized cost using the effective interest method, less any identified impairment losses.

Available-for-sale financial investments

Available-for-sale financial investments are non-derivative financial assets in unlisted equity investments. Equity investments classified as available for sale are those which are neither classified as held for trading nor designated as at fair value through profit or loss.

When the fair value of unlisted equity investments cannot be reliably measured because (a) the variability in the range of reasonable fair value estimates is significant for that investment or (b) the probabilities of the various estimates within the range cannot be reasonably assessed and used in estimating fair value, such investments are stated at cost less any impairment losses.

The Group evaluates whether the ability and intention to sell its available-for-sale financial investments in the near term are still appropriate. When, in rare circumstances, the Group is unable to trade these financial assets due to inactive markets, the Group may elect to reclassify these financial assets if management has the ability and intention to hold the assets for the foreseeable future or until maturity.

Impairment of financial assets

The Group assesses at the end of each reporting period whether there is objective evidence that a financial asset or a group of financial assets is impaired. An impairment exists if one or more events that occurred after the initial recognition of the asset have an impact on the estimated future cash flows of the financial asset or the group of financial assets that can be reliably estimated. Evidence of impairment may include indications that a debtor or a group of debtors is experiencing significant financial difficulty, default or delinquency in interest or principal payments, the probability that they will enter bankruptcy or other financial reorganization and observable data indicating that there is a measurable decrease in the estimated future cash flows, such as changes in arrears or economic conditions that correlate with defaults.

Financial assets carried at amortized cost

For financial assets carried at amortized cost, the Group first assesses whether impairment exists individually for financial assets that are individually significant, or collectively for financial assets that are not individually significant. If the Group determines that no objective evidence of impairment exists for an individually assessed financial asset, whether significant or not, it includes the asset in a group of financial assets with similar credit risk characteristics and collectively assesses them for impairment. Assets that are individually assessed for impairment and for which an impairment loss is, or continues to be, recognized are not included in a collective assessment of impairment.

The amount of any impairment loss identified is measured as the difference between the asset’s carrying amount and the present value of estimated future cash flows (excluding future credit losses that have not yet been incurred). The present value of the estimated future cash flows is discounted at the financial asset’s original effective interest rate (i.e., the effective interest rate computed at initial recognition). The carrying amount of the asset is reduced through the use of an allowance account and the loss is recognized in the consolidated statements of comprehensive income. Interest income continues to be accrued on the reduced carrying amount and is accrued using the rate of interest used to discount the future cash flows for the purpose of measuring the impairment loss. Loans and receivables together with any associated allowance are written off when there is no realistic prospect of future recovery and all collateral has been realized or has been transferred to the Group.

If, in a subsequent period, the amount of the estimated impairment loss increases or decreases because of an event occurring after the impairment was recognized, the previously recognized impairment loss is increased or reduced by adjusting the allowance account. If a write-off is later recovered, the recovery is credited to other expenses in the consolidated statements of comprehensive income.

Available-for-sale financial assets

The amount of the impairment loss is measured as the difference between the asset’s acquisition cost (less any principal repayment and amortization) and current fair value, less any impairment loss on that financial asset previously recognized in profit or loss, and is reclassified from “other comprehensive income” to “profit or loss”. If, in a subsequent period, the fair value of an investment in a debt instrument increases, and the increase can be related objectively to an event occurring after the impairment loss was recognized, then such impairment loss is reversed through profit or loss. Impairment loss of an investment in an equity instrument recognized in profit or loss shall not be reversed through profit or loss. Impairment loss is recognized and reversed by adjusting the carrying amount of the asset directly.

Derecognition of financial assets

A financial asset (or, where applicable, a part of a financial asset or part of a group of similar financial assets) is primarily derecognized (i.e., removed from the Group’s consolidated statement of financial position) when:

•

the rights to receive cash flows from the asset have expired; or

•

the Group has transferred its rights to receive cash flows from the asset or has assumed an obligation to pay the received cash flows in full without material delay to a third party under a “pass-through” arrangement; and either (a) the Group has transferred substantially all the risks and rewards of the asset, or (b) the Group has neither transferred nor retained substantially all the risks and rewards of the asset, but has transferred control of the asset.

When the Group has transferred its rights to receive cash flows from an asset or has entered into a pass-through arrangement, it evaluates if and to what extent it has retained the risk and rewards of ownership of the asset. When it has neither transferred nor retained substantially all the risks and rewards of the asset nor transferred control of the asset, the Group continues to recognize the transferred asset to the extent of the Group’s continuing involvement. In that case, the Group also recognizes an associated liability. The transferred asset and the associated liability are measured on a basis that reflects the rights and obligations that the Group has retained.

Continuing involvement that takes the form of a guarantee over the transferred asset is measured at the lower of the original carrying amount of the asset and the maximum amount of consideration that the Group could be required to repay.

Investments in associates

The Group’s investments in associates are accounted for using the equity method. An associate is an entity over which the Group has significant influence and that is neither a subsidiary nor a joint venture. Significant influence is the power to participate in the financial and operating policy decisions of an entity, but is not control or joint control over those policies. Any difference between the acquisition cost and the Group’s share of the net fair value of the identifiable assets and liabilities of associates is accounted for as follows:

(a)

Any excess of the acquisition cost over the Group’s share of the net fair value of the identifiable assets and liabilities of an associate at the date of acquisition is recognized as goodwill and is included in the carrying amount of the investment. Amortization of goodwill is not permitted.

(b)

Any excess of the Group’s share of the net fair value of the identifiable assets and liabilities of an associate over the acquisition cost, after reassessing the fair value, is recognized as a gain in profit or loss on the acquisition date.

Under the equity method, the investments in associates are carried on the statements of financial position at cost plus post acquisition changes in the Group’s share of profit or loss and other comprehensive income of associates. The Group’s share of changes in associates’ profit or loss and other comprehensive income are recognized directly in profit or loss and other comprehensive income, respectively, of the Group. Distributions received from an associate reduce the carrying amount of the investment. Any unrealized gains and losses resulting from transactions between the Group and the associate are eliminated to the extent of the Group’s interest in the associate.

Upon an associate’s issuance of new shares, if the Group takes up more shares than its original proportionate holding while maintaining its significant influence over that associate, such increase would be accounted for as an acquisition of an additional equity interest in the associate. Upon an associate’s issuance of new shares, if the Group does not take up proportionate shares and reduces its shareholding while maintaining its significant influence over that associate, the Group will treat the transaction as deemed disposal and reclassify to profit or loss the proportion of the gain or loss previously recognized in other comprehensive income relating to that reduction in ownership interest where appropriate.

The Group ceases to use the equity method upon loss of significant influence over an associate. Any difference between the carrying amount of the investment in an associate upon loss of significant influence and the fair value of the retained investment plus proceeds from disposal will be recognized in profit or loss.

The Group determines at each reporting date whether there is any objective evidence that the investments in associates are impaired. An impairment loss, being the difference between the recoverable amount of the associate and its carrying value, is recognized in profit or loss in the consolidated statements of comprehensive income and forms part of the carrying amount of the investments.

Financial liabilities

Initial recognition and measurement

Financial liabilities are classified, at initial recognition, as financial liabilities at fair value through profit or loss, loans and borrowings, or as derivatives designated as hedging instruments in an effective hedge, as appropriate.

All financial liabilities are recognized initially at fair value and, in the case of loans and borrowings, net of directly attributable transaction costs.

The Group’s financial liabilities include bank loans, accounts payable and other monetary liabilities.

Subsequent measurement

The subsequent measurement of financial liabilities depends on their classification as follows:

Loans and borrowings

After initial recognition, interest-bearing loans and borrowings are subsequently measured at amortized cost, using the effective interest rate method unless the effect of discounting would be immaterial, in which case they are stated at cost. Gains and losses are recognized in the consolidated statements of comprehensive income when the liabilities are derecognized through the effective interest rate amortization process.

Amortized cost is calculated by taking into account any discount or premium on acquisition and fees or costs that are an integral part of the effective interest rate. The effective interest rate amortization is included in finance costs in the consolidated statements of comprehensive income.

Notes and accounts payable

Notes and accounts payable are obligations to pay for goods or services that have been acquired in the ordinary course of business from suppliers. They are recognized initially at fair value and subsequently measured at amortized cost using the effective interest method. However, short-term accounts payable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.

Derecognition of financial liabilities

A financial liability is derecognized when the obligation under the liability is discharged or cancelled, or expired. When an existing financial liability is replaced by another from the same lender on substantially different terms, or the terms of an existing liability are substantially modified, such an exchange or modification is treated as a derecognition of the original liability and a recognition of a new liability, and the difference between the respective carrying amounts is recognized in the consolidated statements of comprehensive income.

Dividends

Dividends are recommended by the Board of Directors to the Shareholders’ approval pursuant to the Company’s Article of Incorporation.

Operating lease charges

Where the Group has the use of assets held under operating leases, payments made under the leases are charged to the consolidated statements of comprehensive income in equal installments over the accounting periods covered by the lease term, except where an alternative basis is more representative of the pattern of benefits to be derived from the leased assets. Lease incentives received are recognized in the consolidated statements of comprehensive income as an integral part of the aggregate net lease payments made. Contingent rentals, if any, are charged to the consolidated statements of comprehensive income in the accounting period in which they are incurred.

Treasury stock

Treasury stock is stated at cost and shown as a deduction in equity. When the Company retires treasury stock, the treasury stock account is reduced and the share capital as well as the capital surplus – share premium are reversed on a pro rata basis. When the book value of the treasury stock exceeds the sum of par value and share premium, the difference is charged to respective capital surplus and to retained earnings for any remaining amount. The Company’s stock held by its subsidiary is treated as treasury stock.

Provisions

A provision is recognized when a present obligation (legal or constructive) has arisen as a result of a past event and it is probable that a future outflow of resources will be required to settle the obligation, provided that a reliable estimate can be made of the amount of the obligation.

When the effect of discounting is material, the amount recognized for a provision is the present value at the end of the reporting period of the future expenditures expected to be required to settle the obligation. The increase in the discounted present value amount arising from the passage of time is included in finance costs in the consolidated statements of comprehensive income.

Foreign currency translation

The consolidated financial statements are presented in New Taiwan dollars, which is the Company’s functional currency. Each entity in the Group determines its own functional currency and items included in the financial statements of each entity are measured using that functional currency. Foreign currency transactions are initially recorded using the functional currency rates ruling at the date of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated at the functional currency rates of exchange ruling at the end of the reporting period. All differences are taken to profit or loss. Non-monetary items that are measured in terms of historical cost in a foreign currency are translated using the exchange rates at the dates of the initial transactions. Non-monetary items measured at fair value in a foreign currency are translated using the exchange rates at the date when the fair value was determined. The functional currencies of certain overseas subsidiaries are currencies other than the New Taiwan dollars. As at the end of the reporting period, the assets and liabilities of these entities are translated into the presentation currency of the Company at the exchange rates ruling at the end of the reporting period, and their income and expense items are translated into New Taiwan dollars at the weighted average exchange rates for the year.

The resulting exchange differences are recorded in other comprehensive income and the cumulative balance is included in foreign currency translation reserve in the consolidated statements of changes in equity. On disposal of a foreign entity, the deferred cumulative amount recognized in foreign currency translation reserve relating to that particular foreign operation is recognized in the consolidated statements of comprehensive income. For the purpose of the consolidated statements of cash flows, the cash flows of overseas subsidiaries are translated into New Taiwan dollars at the exchange rates ruling at the dates of the cash flows. Frequently recurring cash flows of overseas subsidiaries which arise throughout the year are translated into New Taiwan dollars at the weighted average exchange rates for the year.

Revenue recognition

Revenue is recognized to the extent that it is probable that the economic benefits arising in the course of business will flow to the Group and the revenue can be reliably measured, regardless of when the payment is being made. Revenue is measured at the fair value of the consideration received or receivable, taking into account contractually defined terms of payment and excluding taxes or duty.

The Group engaged in the research, development, manufacturing and sale of high-integration and high-precision integrated circuits and related assembly and testing services. The criteria that the Group uses to determine when to recognize revenue are: (a) the Group has transferred to the buyer the significant risks and rewards of ownership of the goods; (b) the Group retains neither continuing managerial involvement to the degree usually associated with ownership nor effective control over the goods sold; (c) the amount of revenue can be measured reliably; (d) it is probable that the economic benefits associated with the transaction will flow to the Group ; (e) the stage of completion of the transaction at the end of the reporting period can be measured reliably, and (f) the costs incurred for the transaction and the costs to complete the transaction can be measured reliably.

The Group does not take ownership of: (1) bare semiconductor wafers received from customers that are assembled into finished semiconductors, and (2) assembled semiconductors received from the customers that it tests. The title and risk of loss remains with the customer for those bare semiconductors and/or assembled semiconductors. Accordingly, the customer-supplied semiconductor materials are not included in the consolidated financial statements.

The Group does not provide warranties to customers except in cases of defects in the assembly services provided and deficiencies in testing services provided. An appropriate sales allowance is recognized in the period during which the sale is recognized, and is estimated based on historical experience.

Interest income

Interest income is recognized on an accrual basis using the effective interest method by applying the rate that discounts the estimated future cash receipts through the expected life of the financial instrument to the net carrying amount of the financial asset.

Research and development costs

Research and development costs that do not meet the criteria of internally generated intangible assets of IAS 38 “Intangible Assets” are expensed in the period in which it is incurred.

Borrowing costs

Borrowing costs directly attributable to the acquisition, construction or production of qualifying assets, which are assets that necessarily take a substantial period of time to get ready for their intended use or sale, are added to the cost of those assets, until such time as the assets are substantially ready for their intended use or sale. All other borrowing costs are charged to the consolidated statements of comprehensive income in the period in which they are incurred.

Pension and other post-employment benefits

The Group operates defined contribution and defined benefit plans in the ROC and PRC. For defined contribution retirement benefit plans, payments to the benefit plan are recognized as an expense when the employees have rendered service entitling them to the contribution. For defined benefit retirement plans, the cost of providing benefit is recognized based on actuarial calculations.

For defined benefit retirement benefit plans, the cost of providing benefits is determined using the Projected Unit Credit Method, with actuarial valuations being carried out at the year end. Remeasurements are recognized in other comprehensive income in the period which they incur. Past service costs are recognized in the consolidated statements of comprehensive income on the earlier of the date of the plan amendment or curtailment, and the date that the Group recognizes restructuring-related costs. Net interest is calculated by applying the discount rate to the net defined benefit liability or asset. The Group recognizes i) service costs comprising current service costs, past service costs, gains and losses on curtailments and non-routine settlements, and ii) net interest expense or income, under cost of revenue, research and development expenses, sales and marketing expenses and general and administrative expenses in the consolidated statements of comprehensive income.

Employee entitlements to annual leave are recognized when they accrue to employees. An accrual is made for the estimated liability for annual leave as a result of services rendered by employees up to the end of the reporting period.

Share-based payments

Employees of the Group receive remuneration in the form of share-based payments, whereby employees render services as consideration for equity instruments (equity-settled transactions) or share appreciation rights, which are settled in cash (cash-settled transactions).

Equity-settled transactions

The cost of equity-settled transactions is determined by the fair value at the date when the grant is made using an appropriate valuation model.

That cost is recognized, together with a corresponding increase in capital surplus in equity, over the period in which the performance and/or service conditions are fulfilled in employee benefit expenses. The cumulative expense recognized for equity-settled transactions at each reporting date until the vesting date reflects the extent to which the vesting period has expired and the Group’s best estimate of the number of equity instruments that will ultimately vest.

When the terms of an equity-settled award are modified, as a minimum, the services received measured at the grant date, fair value of the equity instruments granted should be recognized, unless those equity instruments do not vest because of failure to satisfy a vesting condition (other than a market condition) that was specified at grant date. An additional expense is recognized for any modification that increases the total fair value of the share-based payment transaction, or is otherwise beneficial to the employee as measured at the date of modification.

Where an equity-settled award is cancelled, it is treated as if it had vested on the date of cancellation, and any expense not yet recognized for the award is recognized immediately. This includes any award where non-vesting conditions within the control of either the Group or the employee are not met. However, if a new award is substituted for the cancelled award, and is designated as a replacement award on the date that it is granted, the cancelled and new awards are treated as if they were a modification of the original award, as described in the previous paragraph.

Cash-settled transactions

The cost of cash-settled transactions is measured initially at fair value at the grant date using an appropriate valuation model. This fair value is expensed over the period until the vesting date with recognition of a corresponding liability. The liability is re-measured to fair value at each reporting date up to, and including the settlement date, with changes in fair value recognized in employee benefit expenses.

Restricted shares

Restricted shares issued to employees are measured at the fair value of the equity instruments granted at the grant date, and are recognized as compensation cost over the vesting period.

For restricted shares where those shares do not restrict distribution of dividends to employees and employees are not required to return the dividends received if they resign during the vesting period, the Group recognizes the fair value of the dividends received by the employees who are expected to resign during the vesting period as compensation cost at the date of dividends declared.

For restricted shares where employees do not need to pay to acquire those shares, if the employees who resign during the vesting period, the Group will recover and retire those shares at no cost.

Income tax

Income tax represents the sum of current and deferred tax. Income tax relating to items recognized outside profit or loss is recognized outside profit or loss, either in other comprehensive income or directly in equity.

Current tax assets and liabilities are measured at the amount expected to be recovered from or paid to the taxation authorities, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period, taking into consideration interpretations and practices prevailing in the countries in which the Group operates.

Deferred tax is provided, using the liability method, on all temporary differences at the end of the reporting period between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes.

Deferred tax liabilities are recognized for all taxable temporary differences, except:

•

when the deferred tax liability arises from the initial recognition of goodwill or an asset or liability in a transaction that is not a business combination and, at the time of the transaction, affects neither the accounting profit nor taxable profit or loss; and

•

in respect of taxable temporary differences associated with investments in subsidiaries, associates and joint ventures, when the timing of the reversal of the temporary differences can be controlled and it is probable that the temporary differences will not reverse in the foreseeable future.

Deferred tax assets are recognized for all deductible temporary differences, the carryforward of unused tax credits and any unused tax losses. Deferred tax assets are recognized to the extent that it is probable that taxable profits will be available against which deductible temporary differences, the carryforward of unused tax credits and unused tax losses can be utilized, except:

•

when the deferred tax asset relating to the deductible temporary differences arises from the initial recognition of an asset or liability in a transaction that is not a business combination and, at the time of the transaction, affects neither the accounting profit nor taxable profit or loss; and

•

in respect of deductible temporary differences associated with investments in subsidiaries, associates and joint ventures, deferred tax assets are only recognized to the extent that it is probable that the temporary differences will reverse in the foreseeable future and taxable profit will be available against which the temporary differences can be utilized.

The carrying amount of deferred tax assets is reviewed at the end of each reporting period and reduced to the extent that it is no longer probable that sufficient taxable profit will be available to allow all or part of the deferred tax asset to be utilized. Unrecognized deferred tax assets are reassessed at the end of each reporting period and are recognized to the

extent that it has become probable that sufficient taxable profit will be available to allow all or part of the deferred tax asset to be recovered.

Deferred tax is calculated, without discounting, at the tax rates that are expected to apply in the period when the asset is realized or the liability is settled, based on the tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period.

Current income tax assets and liabilities are offset and the net amount reported in the statements of financial position when there is a legally enforceable right to offset the recognized amounts and there is an intention to settle on a net basis or realize the asset and settle the liability simultaneously.

aa)

Cash and cash equivalents

Cash and cash equivalents comprise cash on hand and demand deposits, and short-term highly liquid investments which are readily convertible into known amounts of cash, are subject to an insignificant risk of changes in value, and have a short maturity of generally within three months when acquired.

bb)

Related parties

(a)

A person, or a close member of that person’s family, is related to the Group if that person:

(i)

has control or joint control over the Group;

(ii)

has significant influence over the Group; or

(iii)

is a member of key management personnel of the Group or the Group’s parent.

(b)

An entity is related to the Group if any of the following conditions applies:

(i)

The entity and the Group are members of the same group.

(ii)

One entity is an associate or joint venture of the other entity (or an associate or joint venture of a member of a group of which the other entity is a member).

(iii)

The entity and the Group are joint ventures of the same third party.

(iv)

One entity is a joint venture of a third entity and the other entity is an associate of the third entity.

(v)

The entity is a post-employment benefit plan for the benefit of employees of either the Group or an entity related to the Group.

(vi)

The entity is controlled or jointly controlled by a person identified in (a).

(vii)

A person identified in (a)(i) has significant influence over the entity or is a member of the key management personnel of the entity (or of a parent of the entity).

cc)

Subsidiaries

A subsidiary is an entity (including a structured entity) controlled by the Company. Control is achieved when the Group is exposed, or has rights, to variable returns from its involvement with the investee and has the ability to affect those returns through its power over the investee (i.e., existing rights that give the Group the current ability to direct the relevant activities of the investee).

When the Company has, directly or indirectly, less than a majority of the voting or similar rights of an investee, the Group considers all relevant facts and circumstances in assessing whether it has power over an investee, including:

•

the contractual arrangement with the other vote holders of the investee;

•

rights arising from other contractual arrangements; and

•

the Group’s voting rights and potential voting rights

The Company’s share of its subsidiaries’ post-acquisition profits or losses is recognized in profit or loss, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income. When the Company’s share of losses in a subsidiary equals or exceeds its interest in the subsidiary, the Company continues to recognize its share in the subsidiary’s loss proportionately.

Changes in a parent’s ownership interest in a subsidiary that do not result in the parent losing control of the subsidiary (transactions with non-controlling interests) are accounted for as equity transactions, i.e. transactions with owners in their capacity as owner. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity.

dd)

Fair value measurement

The Group measures its accrued pension cost at fair value at the end of each reporting period. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value measurement is based on the presumption that the transaction to sell the asset or transfer the liability takes place either in the principal market for the asset or liability, or in the absence of a principal market, in the most advantageous market for the asset or liability. The principal or the most advantageous market must be accessible by the Group. The fair value of an asset or a liability is measured using the assumptions that market participants would use when pricing the asset or liability, assuming that market participants act in their economic best interest.

A fair value measurement of a non-financial asset takes into account a market participant’s ability to generate economic benefits by using the asset in its highest and best use or by selling it to another market participant that would use the asset in its highest and best use.

The Group uses valuation techniques that are appropriate in the circumstances and for which sufficient data are available to measure fair value, maximizing the use of relevant observable inputs and minimizing the use of unobservable inputs.

All assets and liabilities for which fair value is measured or disclosed in the financial statements are categorized within the fair value hierarchy, described as follows, based on the lowest level input that is significant to the fair value measurement as a whole:

Level 1 – based on quoted prices (unadjusted) in active markets for identical assets or liabilities

Level 2 – based on valuation techniques for which the lowest level input that is significant to the fair value measurement is observable, either directly or indirectly

Level 3 – based on valuation techniques for which the lowest level input that is significant to the fair value measurement is unobservable

For assets and liabilities that are recognized in the financial statements on a recurring basis, the Group determines whether transfers have occurred between levels in the hierarchy by reassessing categorization (based on the lowest level input that is significant to the fair value measurement as a whole) at the end of each reporting period.

ee)

Capital reorganization

The Company merged with ChipMOS Bermuda on October 31, 2016 and the transaction was accounted as capital reorganization within the Group. When presenting comparative financial statements, the Company presented it as if ChipMOS Bermuda had always been combined and the financial statements were restated retrospectively. The assets and liabilities acquired from ChipMOS Bermuda was measured by using book value method, and any differences between the consideration given by the Company and the aggregate book value of the assets and liabilities of ChipMOS Bermuda was first accounted for as addition (deduction) in capital surplus arises from share premium, if the share premium is insufficient, the amount will be accounted for as deduction from retained earnings. In addition, on the effective date of the Merger, the Company reclassified its shares originally held by ChipMOS Bermuda as treasury stock and cancelled those shares with deduction in share premium equal to the proportion of retired shares. If the share premium is insufficient, the amount will be accounted for as deduction from retained earnings. Transaction costs attributable to the Merger are accounted for as deduction from equity.

When presenting comparative financial statements, the Company presented it as if ChipMOS Bermuda had always been combined and the financial statements were restated retrospectively. Net income attributable to ChipMOS Bermuda prior to the Merger were presented as “Predecessors’ interests”.

Translation into U.S. dollar amounts

12 Months Ended

Dec. 31, 2017

Translation into U.S. dollar amounts

3.	*Translation into U.S. dollar amounts*

The Company maintains its accounts and expresses its consolidated financial statements in New Taiwan dollars. For convenience purposes, U.S. dollar amounts presented in the accompanying consolidated financial statements have been translated from New Taiwan dollars to U.S. dollars at the noon buying rate in the City of New York for cable transfers as certified for customs purposes by the Federal Reserve Bank of New York as of December 29, 2017, which was NT$29.64 to US$1.00. These convenience translations should not be construed as representations that the New Taiwan dollar amounts have been, or could in the future be, converted into U.S. dollars at this or any other rate of exchange.

Segment Information

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Segment Information

4.	*Segment Information*

The Group engages mainly in the assembly and testing of semiconductors, memory module and investing. In accordance with IFRS 8 “Operating Segments”, the Group’s chief operating decision maker has been identified as the Chairman of the Board of Directors, who reviews these segment results by Testing, Assembly, Testing and Assembly for Liquid Crystal Display and other Flat-Panel Display Driver Semiconductors (“LCDD”) and Bumping when making decisions about allocating resources and assessing the performance of the Group. The information of the segments’ other assets and liabilities are not regularly provided to the Chairman of the Board of Directors for decision making. Financial segment information is as below:

The Group uses operating profit (loss) as the measurement for segment profit (loss) and the basis of performance assessment. There was no material inconsistency between the accounting policies of the operating segment and the accounting policies described in Note 2.


	2015
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000
Revenue
External customers		4,546,394			5,525,582			5,396,001			3,369,112			—			—			18,837,089			1,032,302
Inter-segment		172,264			528			—			—			44,577			(217,369	)		—			—

Total revenue		4,718,658			5,526,110			5,396,001			3,369,112			44,577			(217,369	)		18,837,089			1,032,302

Operating profit (loss)		1,203,169			117,127			1,354,398			28,605			(47,191	)		(7,681	)		2,648,427			(61,214	)
Depreciation and amortization		(646,545	)		(550,819	)		(1,157,809	)		(548,234	)		(357	)		543			(2,903,221	)		(118,702	)
Interest income		—			—			—			—			60,552			(1,690	)		58,862			9,421
Interest expense		—			—			—			—			(128,311	)		1,690			(126,621	)		(414	)
Share of profit of associates		—			—			—			—			25,346			5,923			31,269			—
Purchase of property, plant and equipment		796,964			895,767			1,366,389			589,615			2,477			(6,652	)		3,644,560			—


	2016
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000
Revenue
External customers		4,587,054			5,880,780			4,920,302			2,999,457			—			—			18,387,593			1,005,166
Inter-segment		—			1,103			—			510			41,670			(43,283	)		—			—

Total revenue		4,587,054			5,881,883			4,920,302			2,999,967			41,670			(43,283	)		18,387,593			1,005,166

Operating profit (loss)		1,346,874			143,220			963,698			(341,356	)		(82,331	)		(31,530	)		1,998,575			(146,263	)
Depreciation and amortization		(664,026	)		(635,481	)		(1,167,908	)		(622,412	)		(565	)		488			(3,089,904	)		(141,375	)
Interest income		—			—			—			—			51,756			(13,202	)		38,554			3,753
Interest expense		—			—			—			—			(144,545	)		—			(144,545	)		(606	)
Share of profit (loss) of associates		—			—			—			—			(128,866	)		157,790			28,924			—
Purchase of property, plant and equipment		771,500			554,162			910,457			887,144			49			—			3,123,312			1,567,683


	2017
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Total continuing operations			Discontinued operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			US$000			NT$000			US$000
Revenue
External customers		4,838,246			5,259,281			4,789,869			3,053,459			—			—			17,940,855			605,292			227,095			7,662
Inter-segment		—			—			247			—			35,808			(36,055	)		—			—			—			—

Total revenue		4,838,246			5,259,281			4,790,116			3,053,459			35,808			(36,055	)		17,940,855			605,292			227,095			7,662

Operating profit (loss)		1,448,939			(55,198	)		1,285,495			(336,123	)		(100,545	)		(2,687	)		2,239,881			75,570			(25,394	)		(857	)
Depreciation and amortization		(673,393	)		(597,500	)		(1,048,587	)		(579,605	)		(503	)		310			(2,899,278	)		(97,816	)		—			—
Interest income		—			—			—			—			53,123			—			53,123			1,792			464			16
Interest expense		—			—			—			—			(190,425	)		—			(190,425	)		(6,425	)		(2,414	)		(81	)
Share of profit (loss) of associates		—			—			—			—			1,347,851			(1,527,342	)		(179,491	)		(6,056	)		—			—
Purchase of property, plant and equipment		836,894			655,879			2,615,153			594,765			—			—			4,702,691			158,660			—			—

Geographic information of revenue:


	2015		2016		2017		2017
	NT$000		NT$000		NT$000		US$000
Area
ROC		13,529,739		12,728,014		13,152,419		443,739
Japan		986,403		1,855,674		2,257,296		76,157
Singapore		2,928,591		3,087,835		1,798,585		60,681
Others		1,392,356		716,070		732,555		24,715

		18,837,089		18,387,593		17,940,855		605,292

Net revenue from customers representing at least 10% of the total revenue:


	2015				2016				2017				2017
	Amount		%		Amount		%		Amount		%		Amount
	NT$000				NT$000				NT$000				US$000
Customers
Customer A		4,307,855		23		3,370,285		18		3,434,873		19		115,886
Customer K		2,386,975		13		2,633,431		14		2,742,882		15		92,540
Customer I		2,935,820		16		3,085,190		17		1,798,111		10		60,665
Customer C		1,761,049		9		1,870,675		10		1,530,209		9		51,626

The revenue generated from the above customers is mainly from the segments of Assembly and LCDD.

Operating costs and expenses

12 Months Ended

Dec. 31, 2017

Operating costs and expenses

5.	*Operating costs and expenses*


	2015		2016			2017		2017
	NT$000		NT$000			NT$000		US$000
Change of finished goods and work in process		7,899		(19,498	)		31,977		1,079
Consumption of raw materials and supplies		3,271,581		3,346,540			3,036,350		102,441
Employee benefit expenses		5,358,962		5,317,125			5,895,778		198,913
Depreciation and amortization		2,903,221		3,089,904			2,899,278		97,816
Other expenses		4,752,050		4,745,253			4,530,425		152,848

Total operating costs and expenses		16,293,713		16,479,324			16,393,808		553,097

Employee benefit expenses
Salaries		4,300,550		4,126,203			4,874,709		164,464
Labor and health insurance		355,331		351,232			390,788		13,184
Pension		179,665		183,293			198,502		6,697
Share-based payments		207,242		356,463			123,021		4,151
Other personnel expenses		316,174		299,934			308,758		10,417

		5,358,962		5,317,125			5,895,778		198,913

Other operating income (expenses), net

12 Months Ended

Dec. 31, 2017

Other operating income (expenses), net

6.	*Other operating income (expenses), net*


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Gain on disposal of property, plant and equipment, net		1,562			2,575			132,777			4,480
Impairment on property, plant and equipment		(1,460	)		(8,198	)		(956	)		(32	)
Gain on disposal of scrapped materials		31,870			30,476			27,940			943
Gain on disposal of items purchased on behalf of others		22,893			48,812			26,417			891
Royalty income		—			—			11,998			405
Insurance compensation income		—			7,033			486,858			16,426
Others		50,186			9,608			7,800			262

		105,051			90,306			692,834			23,375

Finance costs

12 Months Ended

Dec. 31, 2017

Finance costs

7.	*Finance costs*


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Interest on bank loans		146,003			157,254			208,486			7,034
Interest on lease payable		—			212			708			24
Less: Amounts capitalized in qualifying assets		(19,382	)		(12,921	)		(18,769	)		(633	)

		126,621			144,545			190,425			6,425
Finance expense		15,890			34,571			26,858			906

		142,511			179,116			217,283			7,331

Other non-operating income (expenses), net

12 Months Ended

Dec. 31, 2017

Other non-operating income (expenses), net

8.	*Other non-operating income (expenses), net*


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Interest income		58,862			38,554			53,123			1,792
Foreign exchange gains (losses), net		241,983			(195,326	)		(418,970	)		(14,135	)
Impairment of available-for-sale financial assets		(8,584	)		—			—			—
Gain on disposal of financial assets at fair value through profit or loss		11,483			621			637			22
Gain on disposal of long-term investment in associates		—			—			16,929			571
Share of profit (loss) of associates		31,269			28,924			(179,491	)		(6,056	)
Reimbursement of ADSs service charge		—			—			23,707			800
Others		5,127			8,203			13,883			468

		340,140			(119,024	)		(490,182	)		(16,538	)

Income tax expense

12 Months Ended

Dec. 31, 2017

Income tax expense

9.	*Income tax expense*

Income tax expense arising in other jurisdictions is calculated at the rates prevailing in the relevant jurisdictions, based on existing legislation, interpretations and practices in respect thereof.

The statutory tax rates for the years ended December 31, 2015, 2016 and 2017 for ChipMOS Taiwan and ChipMOS Shanghai were 17% and 25%, respectively. The statutory tax rate for the year ended December 31, 2015 for ThaiLin was 17%.

The major components of income tax expense for the years ended December 31, 2015, 2016 and 2017 are:


	2015			2016			2017		2017
	NT$000			NT$000			NT$000		US$000
Current income tax:
Current income tax on profits for the period		720,461			331,144			125,376		4,230
Income tax (benefit) on unappropriated retained earnings		198,157			(174,930	)		246,684		8,322
Prior year income tax (over) under estimation		(1,732	)		4,527			67,885		2,290

Total current income tax		916,886			160,741			439,945		14,842

Deferred income tax:
Relating to origination and reversal of temporary differences		18,969			16,379			110,542		3,730

Total deferred income tax		18,969			16,379			110,542		3,730

Income tax expense reported in the consolidated statements of comprehensive income		935,855			177,120			550,487		18,572

Unappropriated retained earnings decreased by NT$5,052,343 thousand due to the capital reorganization, and accordingly the Company did not recognize an additional 10% tax on respective unappropriated retained earnings for the year 2015. Information about the capital reorganization for the year ended December 31, 2016 is provided in Note 29.

Deferred tax charged to other comprehensive income:

2015

2016

2017

NT$000

US$000

Remeasurement of defined benefit obligations

(7,099

)

(7,375

)

8,642

292

Reconciliation of income tax expense and the accounting profit before income tax:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Tax calculated based on profit before tax and statutory tax rate		462,692			214,550			566,649			19,118
Expenses disallowed (added) by tax regulations		5,692			(2,190	)		10,185			344
Temporary difference not recognized as deferred tax assets		6,522			1,306			(85,168	)		(2,873	)
Tax exempted (income) expenses by tax regulation		(13,483	)		12,057			(256,788	)		(8,664	)
Taxable loss not recognized as deferred tax assets		25,737			54,012			—			—
Effect of different tax rates in countries in which the Group operates		3,100			10,451			1,040			35
Withholding tax		249,170			57,337			—			—
Prior year income tax (over) under estimation		(1,732	)		4,527			67,885			2,290
Income tax (benefit) on unappropriated retained earnings		198,157			(174,930	)		246,684			8,322

Income tax expense reported in the consolidated statements of comprehensive income		935,855			177,120			550,487			18,572

The details of deferred tax assets (liabilities) are as follows:


	January 1,			Profit and (loss)			Other comprehensive income			December 31,			December 31,
	NT$000			NT$000			NT$000			NT$000			US$000
Year of 2016
Deferred tax assets
Unrealized exchange losses		(5,843	)		5,843			—			—
Inventories		14,823			11,501			—			26,324
Property, plant and equipment		3,672			77,197			—			80,869
Deferred income		50,423			(9,129	)		—			41,294
Provisions		16,473			(5,241	)		—			11,232
Net defined benefit liability, non-current		86,719			(4,007	)		7,375			90,087

Deferred tax assets		166,267			76,164			7,375			249,806

Deferred tax liabilities
Unrealized exchange gains		—			(14,155	)		—			(14,155	)
Property, plant and equipment		—			(78,388	)		—			(78,388	)

Deferred tax liabilities		—			(92,543	)		—			(92,543	)

Year of 2017
Deferred tax assets
Unrealized exchange losses		—			8,167			—			8,167			276
Inventories		26,324			(17,192	)		—			9,132			308
Property, plant and equipment		80,869			(25,375	)		—			55,494			1,872
Deferred income		41,294			(1,809	)		—			39,485			1,332
Provisions		11,232			10,411			—			21,643			730
Net defined benefit liability, non-current		90,087			(2,994	)		(8,642	)		78,451			2,647

Deferred tax assets		249,806			(28,792	)		(8,642	)		212,372			7,165

Deferred tax liabilities
Unrealized exchange gains		(14,155	)		14,155			—			—			—
Property, plant and equipment		(78,388	)		(95,905	)		—			(174,293	)		(5,880	)

Deferred tax liabilities		(92,543	)		(81,750	)		—			(174,293	)		(5,880	)

The Company has not recognized deductible and taxable temporary differences associated with investments as deferred tax assets and liabilities. As of December 31, 2017, the amounts of deductible and taxable temporary differences unrecognized as deferred tax assets and liabilities were NT$28,584 thousand (US$964 thousand) and NT$920,943 thousand (US$31,071 thousand), respectively. As of December 31, 2016, the amount of deductible temporary differences unrecognized as deferred tax assets was NT$534,568 thousand.

The Company’s income tax returns through 2015 have been assessed and approved by the Tax Authority.

The Company’s unappropriated retained earnings were all generated in and after 1998.

The balance of the imputation tax credit account was NT$1,192,119 thousand as of December 31, 2016 and the creditable tax rate was 20.48%. With the abolishment of the imputation tax system under the amendments to the Income Tax Act promulgated in February 2018, the information on the balance of the imputation tax credit account as of December 31, 2017, is no longer disclosed. Please refer to Note 37.

Earnings per share ("EPS")

12 Months Ended

Dec. 31, 2017

Earnings per share ("EPS")

10.

Earnings per share (“EPS”)

Basic EPS amounts are calculated by dividing the profit for the year attributable to equity holders of the Company by the weighted average number of ordinary shares outstanding during the year.

Diluted EPS amounts are calculated by dividing the profit attributable to equity holders of the Company by the weighted average number of ordinary shares outstanding during the year plus the weighted average number of ordinary shares that would be issued on conversion of all the dilutive potential ordinary shares into ordinary shares.

The following reflects the income and share data used in the basic and diluted EPS computations:


	2015
	Amount after income tax			Weighted average number of ordinary shares outstanding*		Earnings per share
Basic earnings per share	NT$000			in thousands		NT$
Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		2,164,557					2.47
- Discontinued operations		(34,233	)				(0.04	)

Equity holders of the Company		2,130,324					2.43
Predecessors’ interests		(291,429	)				(0.33	)

	1,838,895			877,402		2.10

Diluted earnings per share
Employees’ bonuses					10,867
Restricted shares					27

Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		2,164,557					2.44
- Discontinued operations		(34,233	)				(0.04	)

Equity holders of the Company		2,130,324					2.40
Predecessors’ interests		(291,429	)				(0.33	)

	1,838,895			888,296		2.07


	2016
	Amount after income tax			Weighted average number of ordinary shares outstanding*		Earnings per share
Basic earnings per share	NT$000			In thousands		NT$
Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		1,829,327					2.13
- Discontinued operations		(122,105	)				(0.14	)

Equity holders of the Company		1,707,222					1.99
Predecessors’ interests		(306,012	)				(0.35	)

	1,401,210			859,644		1.64

Diluted earnings per share
Employees’ bonuses					3,035
Restricted shares					4,122

Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		1,829,327					2.11
- Discontinued operations		(122,105	)				(0.14	)

Equity holders of the Company		1,707,222					1.97
Predecessors’ interests		(306,012	)				(0.35	)

	1,401,210			866,801		1.62

2017

Amount
after income
tax

Weighted average
number of ordinary
shares outstanding

Earnings
per share

Basic earnings per share

NT$000

In thousands

NT$

US$

Profit attributable to:

Equity holders of the Company

- Continuing operations

981,929

1.16

0.04

- Discontinued operations

1,814,953

2.14

0.07

2,796,882

846,686

3.30

0.11

Diluted earnings per share

Employees’ bonuses

14,034

Restricted shares

5,075

Profit attributable to:

Equity holders of the Company

- Continuing operations

981,929

1.13

0.04

- Discontinued operations

1,814,953

2.10

0.07

2,796,882

865,795

3.23

0.11

The weighted average number of shares takes into account the weighted average effect of changes in treasury stock transaction during the year.

Dividend

12 Months Ended

Dec. 31, 2017

Dividend

11.

Dividend

A dividend of NT$2.09 per share was approved by the shareholders of the Company on May 31, 2016. The dividend of NT$1,792,553 thousand was fully paid on December 19, 2016 to all ordinary shareholders of record at the close of business on December 3, 2016.

A distribution of NT$1.00 per share (including cash distribution from capital surplus of NT$0.70 per share) was approved by the shareholders of the Company on May 26, 2017. The distribution of NT$856,754 thousand (US$28,906 thousand) was fully paid on July 12, 2017 to all ordinary shareholders of record at the close of business on June 19, 2017.

Available-for-sale financial assets

12 Months Ended

Dec. 31, 2017

Available-for-sale financial assets

12.

Available-for-sale financial assets


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Unlisted equity investments, at cost		79,880			49,474			1,669
Less: Allowance for impairment losses		(69,920	)		(28,584	)		(964	)

		9,960			20,890			705

Due to the operation loss and accumulated deficit of VIGOUR TECHNOLOGY Corporation (“VIGOUR”), the Company has recognized full impairment loss of its investments on VIGOUR amounted to NT$41,336 thousand (US$1,395 thousand) in prior years. Based on the Company’s assessment, considering VIGOUR is currently in liquidation process and no residual assets are expected to be available for distributions, the carrying amount of investments and accumulated impairment losses were reclassified to “Other receivables” in the fourth quarter of 2017.

As of December 31, 2016 and 2017, no available-for-sale financial assets were pledged.

Investment in associates

12 Months Ended

Dec. 31, 2017

Investment in associates

13.

Investment in associates

Details of investment in associates are as follows:

Country of
incorporation
and business

Measurement
method

December 31, 2016

December 31, 2017

Investee company

Carrying
amount

Ownership

Carrying
amount

Ownership

NT$000

US$000

JMC ELECTRONICS CO., LTD. (“JMC”)

Kaohsiung
Taiwan

Equity
method

369,329

21.22

373,276

12,593

19.10

ChipMOS Shanghai

Shanghai

PRC

Equity
method

—

3,060,056

103,241

45.02

In January 2017, the Company did not participate in the capital increase of JMC, which reduced the Company’s shareholding from 21.22% to 19.10%. Given that the Company still retains significant influence by holding two seats in JMC’s Board of Directors, JMC was still recognized as “Investment in associates”. As a result of the change in shareholding, the Company recognized disposal gain from long-term investment amounted to NT$16,929 thousand (US$571 thousand) for the year ended December 31, 2017.

On November 30, 2016, the Company’s Board of Directors adopted a resolution to authorize its subsidiary, ChipMOS BVI, to dispose 54.98% of ChipMOS Shanghai’s equity. The equity transfer was completed in March 2017, and subsequently, due to the loss of control but retention of significant influence, ChipMOS Shanghai was excluded from the consolidated financial statements and was accounted for as an investment in associate. Information is provided in Note 18.

In June 2017, ChipMOS BVI participated in ChipMOS Shanghai’s increase of paid-in capital based on its shareholding and paid in total of NT$1,373,486 thousand (US$46,339 thousand).

For the years ended December 31, 2016 and 2017, the Company recognized its share of profit of investments in associates amounted to NT$28,924 thousand and share of loss of NT$179,491 thousand (US$6,056 thousand), respectively.

The tables below provide summarized financial information for the investment in associates that are material to the Group.

Statements of financial position


	JMC
	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Current assets		904,571			833,914			28,134
Non-current assets		876,314			1,161,620			39,191
Current liabilities		(258,513	)		(284,580	)		(9,601	)
Non-current liabilities		(2,491	)		(1,756	)		(59	)

Total net assets		1,519,881			1,709,198			57,665

Group’s share		322,509			326,456			11,014
Goodwill		46,820			46,820			1,579

Carrying amount		369,329			373,276			12,593

Statements of financial position


	ChipMOS Shanghai
	December 31, 2017			December 31, 2017
	NT$000			US$000
Current assets		3,380,641			114,056
Non-current assets		2,766,839			93,348
Current liabilities		(460,054	)		(15,521	)
Non-current liabilities		(489,097	)		(16,501	)

Total net assets		5,198,329			175,382

Group’s share		2,340,506			78,965
Depreciable assets		703,536			23,736
Goodwill		22,118			746
Inter-company transactions and amortization		(6,104	)		(206	)

Carrying amount		3,060,056			103,241

Statements of comprehensive income

JMC

Year ended December 31,

2016

2017

NT$000

US$000

Revenue

1,667,761

1,322,928

44,633

Profit for the year from continuing operations

136,303

4,414

149

Other comprehensive income, net of income tax

(627

)

2,903

Total comprehensive income

135,676

7,317

247

Dividend received from the associate

5,730

14,325

483


	ChipMOS Shanghai
	Year ended December 31,
	2017			2017
	NT$000			US$000
Revenue		1,141,415			38,509

Loss for the year from continuing operations		(348,472	)		(11,757	)
Other comprehensive income, net of income tax		—			—

Total comprehensive income		(348,472	)		(11,757	)

Dividend received from the associate		—			—

According to IFRS 5 “Non-current Assets Held for Sale and Discontinued Operations”, total comprehensive income of ChipMOS Shanghai for the three months ended March 31, 2017 was included in the Group’s consolidated statement of comprehensive income with the adjustments of ceasing to recognize depreciation and amortization expenses and the elimination of inter-company transactions. Information about discontinued operations is provided in Note 18.

Property, plant and equipment, net

12 Months Ended

Dec. 31, 2017

Property, plant and equipment, net

14.

Property, plant and equipment, net


	Land		Buildings			Machinery and equipment			Tools			Other equipment			Construction in progress and equipment to be inspected			Total			Total
	NT$000		NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			US$000
January 1, 2016
Cost		452,738		10,700,236			45,945,380			3,673,636			3,047,001			826,103			64,645,094
Accumulated depreciation and impairment		—		(5,863,556	)		(38,602,675	)		(3,323,862	)		(2,643,441	)		—			(50,433,534	)

		452,738		4,836,680			7,342,705			349,774			403,560			826,103			14,211,560

January 1, 2016		452,738		4,836,680			7,342,705			349,774			403,560			826,103			14,211,560
Additions		—		255,916			934,913			358,413			351,850			2,789,903			4,690,995
Disposals		—		(51	)		(8,624	)		—			(351	)		—			(9,026	)
Reclassifications		—		372,448			1,509,798			22,882			37,373			(1,942,501	)		—
Depreciation expenses		—		(631,233	)		(2,188,976	)		(201,755	)		(206,477	)		—			(3,228,441	)
Impairment losses		—		—			—			—			(8,198	)		—			(8,198	)
Exchange adjustments		—		(45,814	)		(18,196	)		(4,871	)		(11,134	)		(45,689	)		(125,704	)

December 31, 2016		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186

December 31, 2016
Cost		452,738		11,183,278			47,002,228			3,999,894			3,353,413			1,627,816			67,619,367
Accumulated depreciation and impairment		—		(6,395,332	)		(39,430,608	)		(3,475,451	)		(2,786,790	)		—			(52,088,181	)

		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186
Less: Property, plant and equipment classified as held for sale		—		(710,191	)		(433,688	)		(90,460	)		(168,314	)		(631,315	)		(2,033,968	)

		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218

January 1, 2017
Cost		452,738		11,183,278			47,002,228			3,999,894			3,353,413			1,627,816			67,619,367			2,281,355
Accumulated depreciation and impairment		—		(6,395,332	)		(39,430,608	)		(3,475,451	)		(2,786,790	)		—			(52,088,181	)		(1,757,361	)

		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186			523,994
Less: Property, plant and equipment classified as held for sale		—		(710,191	)		(433,688	)		(90,460	)		(168,314	)		(631,315	)		(2,033,968	)		(68,622	)

		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218			455,372

January 1, 2017		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218			455,372
Additions		—		211,098			2,007,767			571,601			195,957			1,716,268			4,702,691			158,660
Disposals		—		—			(30,066	)		(2,302	)		(1,865	)		—			(34,233	)		(1,155	)
Reclassifications		—		141,400			1,535,619			44,882			22,149			(1,744,050	)		—			—
Depreciation expenses		—		(511,167	)		(1,837,482	)		(357,695	)		(192,934	)		—			(2,899,278	)		(97,816	)
Impairment losses		—		—			—			—			(956	)		—			(956	)		(32	)
Exchange adjustments		—		—			(43	)		—			(88	)		—			(131	)		(5	)

December 31, 2017		452,738		3,919,086			8,813,727			690,469			420,572			968,719			15,265,311			515,024

December 31, 2017
Cost		452,738		9,809,970			45,778,207			4,004,703			2,624,083			968,719			63,638,420			2,147,045
Accumulated depreciation and impairment		—		(5,890,884	)		(36,964,480	)		(3,314,234	)		(2,203,511	)		—			(48,373,109	)		(1,632,021	)

		452,738		3,919,086			8,813,727			690,469			420,572			968,719			15,265,311			515,024

As of December 31, 2016 and 2017, certain of the above property, plant and equipment were pledged as collateral for long-term bank loans (Notes 32).

2016

2017

NT$000

US$000

Capitalization interest

13,435

18,769

633

Capitalization interest rate applied

1.7456%~3.6166%

1.7624%

Inventories

12 Months Ended

Dec. 31, 2017

Inventories

15.

Inventories


	December 31, 2016
	Cost		Allowance for impairment losses			Carrying amount
	NT$000		NT$000			NT$000
Raw materials		1,787,810		(140,463	)		1,647,347
Work in process		190,823		(14,203	)		176,620
Finished goods		54,190		(175	)		54,015

		2,032,823		(154,841	)		1,877,982


	December 31, 2017
	Cost		Allowance for impairment losses			Carrying amount
	NT$000		NT$000			NT$000		US$000
Raw materials		1,769,917		(49,183	)		1,720,734		58,054
Work in process		180,252		(4,163	)		176,089		5,941
Finished goods		32,784		(368	)		32,416		1,094

		1,982,953		(53,714	)		1,929,239		65,089

The cost of inventories recognized as an expense for the year:


	2016		2017			2017
	NT$000		NT$000			US$000
Cost of revenue		14,670,711		14,766,555			498,197
Loss on abandonment		7,098		38,301			1,292
Allowance for (reversal of) inventory valuation and obsolescence loss		67,663		(101,127	)		(3,412	)

		14,745,472		14,703,729			496,077

Raw materials are utilized throughout the course of provision of semiconductor bumping, assembly and testing services. Items used for manufacturing and product sales are insignificant.

Reversal of allowance for inventory valuation loss was recognized due to the change in market value of replacement costs.

As of December 31, 2016 and 2017, no inventories were pledged.

Accounts and notes and other receivables

12 Months Ended

Dec. 31, 2017

Accounts and notes and other receivables

16.

Accounts and notes and other receivables


	December 31, 2016			December 31, 2017		December 31, 2017
	NT$000			NT$000		US$000
Accounts receivable		4,138,580			4,013,705		135,415
Notes receivable		1,753			2,029		69
Less: Allowance for impairment losses		(87	)		—		—

		4,140,246			4,015,734		135,484

Other receivables		57,411			56,716		1,914
Less: Allowance for impairment losses		—			—		—

		57,411			56,716		1,914

		4,197,657			4,072,450		137,398

As of December 31, 2016 and 2017, no accounts and notes and other receivables were pledged.

The movements in allowance for impairment of accounts and other receivables during the years are as follows:


	Accounts receivable			Other receivables
	NT$000			NT$000
January 1, 2016		—			—
Impairment losses recognized		87			—

December 31, 2016		87			—
Reversal of allowance for impairment losses		(87	)		—

December 31, 2017		—			—

December 31, 2017 (US$000)		—			—

Receivables that were neither past due nor impaired relate to a large number of diversified customers for whom there was no recent history of default.

Receivables that were past due but not impaired relate to a number of independent customers that have a good track record with the Group. Based on past experience, the management of the Company are of the opinion that no provision for impairment is necessary in respect of these balances as there has not been a significant change in credit quality and the balances are still considered fully recoverable.

The individually impaired receivables related to customers that were in financial difficulties or other factors, e.g. the customers were in default or delinquency in interest or principal payments and only a portion of the receivables is expected to be recovered.

The Group’s accounts receivable that were neither past due nor impaired were fully performed in line with the credit standards prescribed based on counterparties’ industrial characteristics, scale of business and profitability.

Ageing of accounts receivable which are past due but not impaired is as follows:


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
£ 1 month		24,141		10,482		354
1 – 2 months		728		477		16
2 – 3 months		183		426		14
3 – 4 months		245		1,431		48
> 4 months		2,013		3,056		103

		27,310		15,872		535

Cash and cash equivalents

12 Months Ended

Dec. 31, 2017

Cash and cash equivalents

17.

Cash and cash equivalents


	December 31, 2016			December 31, 2017		December 31, 2017
	NT$000			NT$000		US$000
Short-term deposits		3,854,354			3,883,614		131,026
Cash		525			470		16
Cash at banks		4,106,384			4,151,630		140,068

		7,961,263			8,035,714		271,110
Less: Cash and cash equivalents classified as non-current assets held for sale		(389,897	)		—		—

		7,571,366			8,035,714		271,110

The cash and cash equivalents of ChipMOS Shanghai as of December 31, 2016, amounted to NT$389,897 thousand was classified and shown as “Non-current assets held for sale”. Information is provided in Note 18.

Cash at banks earns interest at floating rates based on daily bank deposit rates. Short-term deposits are made for varying periods of between 31 days and 3 months, depending on the immediate cash requirements of the Group, and earn interest at the respective short-term deposit rates.

As of December 31, 2016 and 2017, no cash and cash equivalents were pledged.

Non-current assets held for sale and discontinued operations

12 Months Ended

Dec. 31, 2017

Non-current assets held for sale and discontinued operations

18.

Non-current assets held for sale and discontinued operations

The assets and liabilities related to ChipMOS Shanghai have been classified as non-current assets held for sale and liabilities directly related to non-current assets held for sale and presented as discontinued operations for meeting the definition of discontinued operations following the resolution of the Company’s Board of Directors on November 30, 2016 to sell 54.98% of ChipMOS Shanghai’s equity interest. The transaction was completed in March 2017, and subsequently, due to the loss of control but retention of significant influence, ChipMOS Shanghai was excluded from the consolidated financial statements and recorded as “Investments in associates”. Please refer to Note 13 for more details.

In March 2017, the Company received NT$2,230,544 thousand (US$75,255 thousand) in cash and recognized total gain on disposal of discontinued operations amounted to NT$1,843,234 thousand (US$62,187 thousand). Based on the fair value received and the book value of its investment, gain on disposal of 54.98% equity interest is equal to NT$999,630 thousand (US$33,726 thousand) and gain on fair value remeasurement of 45.02% retained investment is equal to NT$843,604 thousand (US$28,461 thousand).

The cash flow information of the discontinued operations is as follows:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Net cash generated from (used in) operating activities		1,072,628			(1,109,029	)		(109,079	)		(3,680	)
Net cash used in investing activities		(205,292	)		(1,331,564	)		(272,925	)		(9,208	)
Net cash generated from (used in) financing activities		(91,234	)		1,463,664			461,312			15,564
Effect of foreign exchange rate changes		(18,636	)		(61,336	)		(19,874	)		(671	)

Net increase (decrease) in cash and cash equivalents		757,466			(1,038,265	)		59,434			2,005

Assets of disposal group classified as non-current assets held for sale:


	December 31,
	2016
	NT$000
Cash and cash equivalents		389,897
Accounts receivable		230,523
Other receivables		202,909
Inventories		136,842
Prepayments		15,943
Other current financial assets		1,193
Property, plant and equipment, net		2,033,968
Refundable deposits		113
Prepaid rent – non-current portion		82,291
Other non-current assets		11,392

		3,105,071

Liabilities of disposal group classified as liabilities directly related to non-current assets held for sale :


	December 31,
	2016
	NT$000
Accounts payable		98,973
Other payables		177,178
Receipts in advance		6,687
Bank loans – current portion		7,614
Lease payable – current		27,702
Other current liabilities		34,276
Bank loans – non-current		106,461
Lease payable – non-current		27,702
Long-term deferred revenue		100,395
Guarantee deposits		651

		587,639

Equity of disposal group classified as amounts recognized in other comprehensive income and accumulated in equity relating to non-current assets held for sale :


	December 31,
	2016
	NT$000
Foreign currency translation reserve		287,645

Cumulative income or expense recognized in other comprehensive income relating to disposal group classified as held for sale:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Exchange differences on translation of foreign operations		(27,893	)		(195,972	)		(287,645	)		(9,705	)

The results of discontinued operations are as follows:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Revenue		1,032,302			1,005,166			227,095			7,662
Cost of revenue		(1,050,075	)		(986,004	)		(195,078	)		(6,582	)
Operating expenses		(51,910	)		(179,178	)		(58,840	)		(1,985	)
Other operating income (expenses), net		8,469			13,753			1,429			48
Non-operating income (expenses), net		26,981			24,158			(2,887	)		(97	)

Loss from discontinued operations before income tax		(34,233	)		(122,105	)		(28,281	)		(954	)
Income tax expense		—			—			—			—

Loss from discontinued operations after income tax		(34,233	)		(122,105	)		(28,281	)		(954	)
Gain on disposal of discontinued operations		—			—			1,843,234			62,187

Profit (loss) from discontinued operations		(34,233	)		(122,105	)		1,814,953			61,233

Discontinued operations’ revenue is mainly from the segments of testing and assembly.

Issued capital

12 Months Ended

Dec. 31, 2017

Issued capital

19.

Issued capital

December 31,
2015

December 31,
2016

December 31,
2017

in thousands

Authorized shares

Ordinary shares

970,000

1,450,000

970,000

December 31,
2015

December 31,
2016

December 31,
2017

in thousands

Ordinary shares issued and fully paid

Ordinary shares

896,206

886,966

886,297

Issued capital (NT$000)

8,962,066

8,869,663

8,862,971

(US$299,021
thousand

)

The par value of ordinary shares issued was NT$10 per share.

The movement of ordinary shares issued is set out below:


	2015			2016			2017
	in thousands			in thousands			in thousands
January 1		864,619			896,206			886,966
Transactions with non-controlling interests (Note 28)		35,932			—			—
Restricted shares		15,752			435			—
Unearned restricted shares – cancelled		(97	)		—			(669	)
Share cancellation		(20,000	)		—			—
Issuance of ordinary shares for capital reorganization (Note 29)		—			512,405			—
Cancellation of ordinary shares from capital reorganization (Note 29)		—			(522,080	)		—

December 31		896,206			886,966			886,297

On June 17, 2015, ThaiLin merged with the Company, with the latter being the surviving entity and issued 35,932 thousand ordinary shares in order to exchange for the shares of ThaiLin. Information about the merge is provided in Note 28.

The Board of Directors approved the issuance of restricted shares on July 14, 2015 (Refer to Note 35). Other than the vesting conditions, the rights and obligations of these shares issued are the same as those of other issued ordinary shares.

On August 10, 2015, the Board of Directors of the Company approved a share repurchase program for repurchase of ordinary shares by the Company of up to NT$826,800 thousand. As of December 31, 2015, 20,000 thousand shares were repurchased and recorded as treasury stock and all the repurchased shares were retired and cancelled.

On February 4, 2016 and May 12, 2016, the Board of Directors of the Company approved the share repurchase programs for repurchase of ordinary shares by the Company of up to NT$600 million and NT$600 million, respectively. As of December 31, 2016 and 2017, 30,000 thousand shares were repurchased and recorded as treasury stock.

On October 31, 2016, the Company’s former parent company, ChipMOS Bermuda was merged with and into the Company, with the latter being the surviving company. Please refer to Note 29 for details of the capital reorganization. Pursuant to the Merger, the Company issued 25,620,267 units of ADSs, which were listed on the NASDAQ Global Select Market, and each ADS represents 20 ordinary shares of the Company. As of December 31, 2017, the outstanding ADSs were 9,431,486 units representing 188,630 thousand ordinary shares of the Company. Major terms and conditions of the ADSs are summarized as follows:

Voting rights:

ADSs holders will have no right to vote directly in shareholders’ meetings with respect to the deposited shares. The depository bank shall vote on behalf of the ADSs holders or provide voting instruction to the designated person of the Company. The depository bank shall vote in the manner as instructed from the ADSs holders.

Distribution of dividends:

ADSs holders are deemed to have the same rights as holders of ordinary shares with respect to the distribution of dividends.

Capital surplus and retained earnings

12 Months Ended

Dec. 31, 2017

Capital surplus and retained earnings

20.

Capital surplus and retained earnings

The reconciliation between the opening and closing balances of each component of the Group’s consolidated equity is set out in the consolidated statements of changes in equity.

Capital surplus

Details of the Group’s capital surplus are set out below:


	December 31, 2015		December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		NT$000		US$000
Share premium		2,501,767		6,473,471		5,873,743		198,169
Share-based payment		849,482		—		—		—
Restricted shares		397,296		408,051		390,401		13,171
Others		7,304		7,304		7,304		247

		3,755,849		6,888,826		6,271,448		211,587

Pursuant to the ROC Company Act, capital surplus arising from paid-in capital in excess of par value on issuance of ordinary shares and donations can be used to cover accumulated deficit or to issue new stocks or cash to shareholders in proportion to their share ownership, provided that the Company has no accumulated deficit. Further, the ROC Securities and Exchange Act requires that the amount of capital surplus to be capitalized mentioned above should not exceed 10% of the paid-in capital each year. Capital surplus should not be used to cover accumulated deficit unless the legal reserve is insufficient.

Retained earnings

(a)

According to the Company’s Articles of Incorporation, current year’s earnings before tax, if any, shall be distributed in the following order:

Pay all taxes and duties;

ii)

Offset prior years’ operating losses, if any;

iii)

Set aside 10% of the remaining amount after deducting i) and ii) as legal reserve;

iv)

After items i), ii) and iii) were deducted, the remaining amount may be distributed as shareholders’ dividend.

(b)

The Company’s dividend policy is summarized below: as the Company operates in a volatile business environment, the dividend is distributed taking into consideration the Company’s financial structure, operating results and future expansion plans. The earnings distribution of the Company may be made by way of cash dividend or stock dividend; provided that cash dividends shall account for at least 10% of the total dividends distributed. The earnings distribution will be proposed by the Board of Directors and approved at the shareholders’ meeting.

(c)

Legal reserve can only be used to offset deficits or increase capital in issuing ordinary shares or in distribution cash. The amount of legal reserve that may be used to increase capital or distribute cash shall be limited to the portion of the reserve balance exceeding 25% of the capital stock.

(d)

In accordance with the ROC Securities and Future Bureau regulations, in addition to legal reserve, the Company should set aside a special reserve in an amount equal to the net change in the reduction of prior year’s shareholders’ equity, resulting from adjustments. Such special reserve is not available for dividend distribution. In the subsequent year(s), if the year-end balances no longer had a net reduction in the shareholders’ equity, the special reserve previously set aside will then be available for distribution.

(e)

The distribution of 2014, 2015 and 2016 were resolved at the shareholders’ meetings on June 3, 2015 and May 31, 2016 and May 26, 2017, respectively. Details are summarized below:


	2014				2015				2016
	Amount		Distribution per share		Amount		Distribution per share		Amount		Distribution per share
	NT$000		NT$		NT$000		NT$		NT$000		NT$
Legal reserve		331,863		—		223,047		—		28,680		—
Cash dividend		1,999,225		2.22		1,792,553		2.09		257,026		0.30
Cash distribution from capital surplus		—		—		—		—		599,728		0.70

Treasury stock

12 Months Ended

Dec. 31, 2017

Long-term bank loans [Member]

Treasury stock

21.

Treasury stock

The movement of treasury stock is set out below:


	2015						2016				2017
	Shares (in thousands)			Amount (NT$000)			Shares (in thousands)		Amount (NT$000)		Shares (in thousands)		Amount (NT$000)		Amount (US$000)
January 1		—			—			—		—		30,085		1,007,654		33,997
Treasury stock (repurchased)		20,000			633,737			30,085		1,007,654		—		—		—
Treasury stock (cancelled)		(20,000	)		(633,737	)		—		—		—		—		—

December 31		—			—			30,085		1,007,654		30,085		1,007,654		33,997

Pursuant to the ROC Securities and Exchange Act, the number of shares repurchased as treasury stock should not exceed 10% of the number of the Company’s issued and outstanding shares and the amount repurchased should not exceed the sum of retained earnings, paid-in capital in excess of par value and realized capital surplus.

Pursuant to the ROC Securities and Exchange Act, treasury stock should not be pledged as collateral and is not entitled to dividends before it is reissued.

Bank loans

12 Months Ended

Dec. 31, 2017

Bank loans

22.

Long-term bank loans


Type of loans	Period and payment term	December 31, 2016			December 31, 2017			December 31, 2017
		NT$000			NT$000			US$000
Syndicated bank loan	Borrowing period is from June 30, 2016 to June 30, 2021; interest is repayable monthly; principal is repayable semi-annually from December 30, 2017.		10,800,000			9,675,301			326,427
Less: Fee on syndicated bank loan			(49,995	)		(33,280	)		(1,122	)
Less: Current portion (fee included)			(1,062,285	)		(2,143,168	)		(72,307	)

			9,687,720			7,498,853			252,998

Interest rate range			1.7895	%		1.7895	%		1.7895	%

Unused credit lines of long-term bank loans NT$000			2,400,000			2,400,000

On May 16, 2016, the Company entered into a syndicated loan with ten banks in Taiwan, including Land Bank of Taiwan, in the amount of NT$13.2 billion with a term of five years. Funding from this syndicated loan was used to repay the prior syndicated loan in 2014 and broaden the Company’s working capital. Pursuant to the syndicated loan agreement, the Group is required to maintain certain financial ratios including current ratio, interest protection multiples and debt to equity ratio during the loan periods.

As of December 31, 2016 and 2017, the Group was in compliance with the financial ratio requirements.

The Group’s bank loans are mortgaged by certain land, buildings and equipment as collateral (Note 32).

Details of the repayment schedule in respect of the bank loans are as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Less than 1 year

1,062,285

2,143,168

72,307

2 to 5 years

9,687,720

7,498,853

252,998

10,750,005

9,642,021

325,305

Short-term bank loans [member]

Bank loans

26.

Short-term bank loans

December 31,
2016

December 31,
2017

NT$000

US$000

Unsecured bank loans

—

969,353

32,704

Annual interest rate

—

0.55%~1.71%

Unused credit lines of short-term bank loans are as follows:


	December 31, 2016		December 31, 2017
NT$000		3,119,000		3,028,357
US$000		80,000		80,000

Retirement benefit plans

12 Months Ended

Dec. 31, 2017

Retirement benefit plans

23.

Retirement benefit plans

Defined benefit plans

(a)

The Company has a defined benefit pension plan in accordance with the Labor Standards Act, covering all regular employees’ service years prior to the enforcement of the Labor Pension Act on July 1, 2005 and service years thereafter of employees who chose to continue to be subject to the pension mechanism under the Act. Under the defined benefit pension plan, two units are accrued for each year of service for the first 15 years and one unit for each additional year thereafter, subject to a maximum of 45 units. Pension benefits are based on the number of units accrued and the average monthly salaries and wages of the last 6 months prior to retirement.

The Company contributes monthly an amount equal to 2% of the employees’ monthly salaries and wages to the pension fund deposited with Bank of Taiwan, the trustee, under the name of the independent pension fund committee. Also, the Company would assess the balance in the aforementioned labor pension reserve account by the end of every year. If the account balance is insufficient to pay the pension calculated by the aforementioned method, to the labors expected to be qualified for retirement next year, the Company will make contribution to cover the deficit by March of following year.

(b)

The amounts recognized in the statements of financial position are as follows:


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Present value of defined benefit obligations		(894,163	)		(838,543	)		(28,291	)
Fair value of plan assets		347,195			360,017			12,146

Net defined benefit liability		(546,968	)		(478,526	)		(16,145	)

(c)

Movements in net defined benefit liability are as follows:


	2016
	Present value of defined benefit obligations			Fair value of plan assets			Net defined benefit liability
	NT$000			NT$000			NT$000
January 1		(844,166	)		324,695			(519,471	)
Current service cost		(321	)		—			(321	)
Interest (expense) income		(14,644	)		5,768			(8,876	)

		(859,131	)		330,463			(528,668	)

Remeasurements:
Return of plan assets (not including the amount included in interest income or expense)		—			(3,413	)		(3,413	)
Financial assumption movement effect		(31,294	)		—			(31,294	)
Experience adjustments		(8,676	)		—			(8,676	)

		(39,970	)		(3,413	)		(43,383	)

Pension fund contribution		—			25,083			25,083
Paid pension		4,938			(4,938	)		—

December 31		(894,163	)		347,195			(546,968	)


	2017
	Present value of defined benefit obligations			Fair value of plan assets			Net defined benefit liability			Net defined benefit liability
	NT$000			NT$000			NT$000			US$000
January 1		(894,163	)		347,195			(546,968	)		(18,454	)
Current service cost		(386	)		—			(386	)		(13	)
Interest (expense) income		(13,236	)		5,226			(8,010	)		(270	)

		(907,785	)		352,421			(555,364	)		(18,737	)

Remeasurements:
Return of plan assets (not including the amount included in interest income or expense)		—			(1,842	)		(1,842	)		(62	)
Financial assumption movement effect		28,506			—			28,506			962
Experience adjustments		24,174			—			24,174			815

		52,680			(1,842	)		50,838			1,715

Pension fund contribution		—			26,000			26,000			877
Paid pension		16,562			(16,562	)		—			—

December 31		(838,543	)		360,017			(478,526	)		(16,145	)

(d)

The Bank of Taiwan was commissioned to manage the Fund of the Company’s defined benefit pension plan (the “Fund”) in accordance with the Fund’s annual investment and utilization plan and the “Regulations for Revenues, Expenditures, Safeguard and Utilization of the Labor Retirement Fund” (Article 6: The scope of utilization for the Fund includes deposit in domestic or foreign financial institutions, investment in domestic or foreign listed, over-the-counter, or private placement equity securities, investment in domestic or foreign real estate securitization products, etc.). With regard to the utilization of the Fund, its minimum earnings in the annual distributions on the final financial statements shall be no less than the earnings attainable from the amounts accrued from two-year time deposits with the interest rates offered by local banks. If the earning is less than aforementioned rates, government shall make payment for the deficit after authorized by the Regulator. The Company has no right to participate in managing and operating that fund and hence the Company is unable to disclose the classification of plan asset fair value in accordance with IAS 19 “Employee Benefits” paragraph 142. The constitution of fair value of plan assets as of December 31, 2016 and 2017 is given in the Annual Labor Retirement Fund Utilization Report announced by the government.

(e)

The principal actuarial assumptions used were as follows:


	2016			2017
Discount rate used in determining present values		1.50	%		1.75	%
Expected future salary increases		3.50	%		3.50	%

Assumptions regarding future mortality are set based on actuarial advice in accordance with published statistics and experience in each territory.

Because the main actuarial assumption changed, the present value of defined benefit obligations is affected. The sensitivity analysis of present value of defined benefit obligations effected by the changes of significant actuarial assumptions at December 31, 2016 and 2017 are shown below:


	Discount rate					Future salary increases
	Increase 0.25%			Decrease 0.25%		Increase 0.25%		Decrease 0.25%
December 31, 2016
Effect on present value of defined benefit obligations		(31,294	)		32,893		32,174		(30,787	)

December 31, 2017
Effect on present value of defined benefit obligations		(27,192	)		28,506		27,955		(26,816	)

The sensitivity analysis above is based on other conditions are unchanged but only one assumption is changed. In practice, more than one assumption may change all at once. The method of sensitivity analysis and the method of calculating net pension liability in the statements of financial position are the same.

The major assumptions of the actuarial valuation remain unchanged from 2016.

(f)

The Group expects to make contributions of NT$26,910 thousand (US$908 thousand) during 2018.

(g)

As of December 31, 2017, the weighted average duration of that retirement plan is 13.4 years. The analysis of timing of the future pension payment is as follows:


	December 31, 2017
	NT$000		US$000
Within 1 year		28,007		945
1-2 years		31,702		1,070
2-5 years		102,703		3,465
6-10 years		178,720		6,029

		341,132		11,509

Defined contribution plans

Effective July 1, 2005, the Company established a defined contribution pension plan (the “New Plan”) under the Labor Pension Act, covering all regular employees with ROC nationality. Under the New Plan, the Company contributes monthly an amount based on 6% of the employees’ monthly salaries and wages to the employees’ individual pension accounts at the Bureau of Labor Insurance. The benefits accrued are paid monthly or in lump sum upon termination of employment. The pension costs under defined contribution pension plans of the Company for the years ended December 31, 2016 and 2017 were NT$174,096 thousand and NT$190,106 thousand (US$6,414 thousand), respectively.

Other Payables

12 Months Ended

Dec. 31, 2017

Other Payables

24.

Other Payables


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
Salaries and bonus payable		443,993		601,239		20,285
Interest payable		1,059		2,854		96
Accrued pension costs		29,930		32,402		1,093
Employees’ bonus		70,553		371,912		12,548
Directors’ remuneration		3,528		18,596		627
Other expense payable		862,991		953,179		32,159

		1,412,054		1,980,182		66,808

Provisions - current

12 Months Ended

Dec. 31, 2017

Provisions - current

25.

Provisions – current

Movements

in provisions are as follows:


	2017
	Provisions for sales allowance			Provisions for deficiency compensation			Total			Total
	NT$000			NT$000			NT$000			US$000
January 1		66,065			14,654			80,719			2,723
Provision		117,234			119,318			236,552			7,981
Payment		(113,143	)		(76,817	)		(189,960	)		(6,409	)

December 31		70,156			57,155			127,311			4,295

The Company’s provisions include sales allowance and deficiency compensation. The detailed information is provided in

Note 2 e).

Significant commitments and contingencies

12 Months Ended

Dec. 31, 2017

Significant commitments and contingencies

27.

Significant commitments and contingencies

Operating leases commitments

ChipMOS Taiwan entered into several operating lease contracts for land. These renewable operating leases will expire by 2032 and 2034.

ChipMOS USA entered into several operating lease contracts for office space. These renewable operating leases will expire by 2018 and 2019.

Future minimum lease payments under those leases are as follows:


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
£ 1 year		39,929		39,342		1,327
2 to 5 years		140,328		130,182		4,392
> 5 years		176,897		139,899		4,720

		357,154		309,423		10,439

Capital commitments

Capital expenditures that are contracted for, but not provided for are as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Property, plant and equipment

1,615,460

2,178,262

73,491

Other commitments

A letter of guarantee was issued by Bank of Taiwan to the Tariff Bureau of the Ministry of Finance for making payment of customs-duty deposits when importing. The amount of letter of guarantee will occupy the credit lines for short-term loans of ChipMOS Taiwan. As of December 31, 2016 and 2017, the amount of NT$131,000 thousand and NT$97,500 thousand (US$3,289 thousand) are guaranteed by Bank of Taiwan.

As described in Note 29, as of October 31, 2016, the Company merged with its former parent company, ChipMOS Bermuda and as a result, the Company deducted unappropriated retained earnings by NT$5,052,343 thousand. The Company has filed an application to the National Taxation Bureau of the Northern Area, Ministry of Finance to apply the accumulated deficit amount, resulted from subtracting the aforementioned amount, as a deduction in the calculation of years 2015 and 2016 additional 10% tax on unappropriated retained earnings.

Transactions with non-controlling interests

12 Months Ended

Dec. 31, 2017

Transactions with non-controlling interests

28.

Transactions with non-controlling interests

The merger of ChipMOS Taiwan and ThaiLin was approved by the respective shareholders at the special shareholders’ meetings held on December 30, 2014 and was completed on June 17, 2015 and ChipMOS Taiwan is the surviving entity. ThaiLin’s shareholders were offered a combination of NT$12.5 in cash and 0.311 of one ChipMOS Taiwan ordinary share in exchange for each ThaiLin ordinary share held. ChipMOS Taiwan issued 35,932 thousand shares and paid NT$1,444,224 thousand in cash to exchange for 52.46% of ThaiLin’s shares. The transaction was treated as an equity transaction. The difference between the amount by which the non-controlling interest is adjusted and the fair value of the consideration paid was recognized in equity attributed to the Company. Before the merger, ChipMOS Taiwan held 47.54% of the outstanding shares of ThaiLin, ThaiLin held 100% of the outstanding shares of ChipMOS BVI and ChipMOS BVI held 100% of the outstanding shares of ChipMOS Shanghai. After the merger, ChipMOS BVI and its wholly-owned subsidiary, ChipMOS Shanghai, became wholly-owned subsidiaries of ChipMOS Taiwan.

The effect on the equity attributed to the Company during the period is summarized as follows:


	2015
	NT$000
Carrying amount of non-controlling interests acquired		2,637,316
Consideration paid to non-controlling interests		(2,921,041	)
Other component of equity		(17,964	)
Capital surplus		26,189

Retained earnings		(275,500	)

Capital reorganization

12 Months Ended

Dec. 31, 2017

Capital reorganization

29.

Capital reorganization

To integrate resources, the Company’s former parent company, ChipMOS Bermuda, was merged with and into the Company as of October 31, 2016, the record date of the Merger, with the latter being the surviving entity and ChipMOS Bermuda being the dissolved entity. Under the Merger Agreement, each shareholder of ChipMOS Bermuda is entitled to receive, with respect to each ChipMOS Bermuda share, 0.9355 units of the Company’s newly-issued ADSs trading on the NASDAQ Global Select Market (each ADS unit represents 20 shares of the Company’s ordinary shares) and US$3.71 in cash. The Company issued 25,620,267 units of ADSs (representing 512,405 thousand ordinary shares) and paid US$101,657 thousand in cash (equivalent to NT$3,208,310 thousand) as the total consideration. In addition, the Company paid NT$133,311 thousand directly attributable transaction cost for the capital reorganization. As the result, the Company paid NT$3,341,621 thousand in cash for the capital reorganization.

The Company issued 512,405 thousand shares for the capital reorganization, and reduced capital by cancelling 522,080 thousand shares originally held by ChipMOS Bermuda. After the capital reorganization, the Company’s shares was net decreased by 9,675 thousand shares. When cancelling treasury stocks, the Company deducted capital surplus equal to the proportion of cancelled shares. Due to the deficit in capital surplus, the Company deducted unappropriated retained earnings by NT$5,052,343 thousand.

As of October 30, 2016, the ending balance of “Predecessors’ interests” was NT$1,692,918 thousand, which represents ChipMOS Bermuda’s net assets as if it had always been combined. The amount has been eliminated in the record date of the Merger.

Supplementary cash flow information

12 Months Ended

Dec. 31, 2017

Supplementary cash flow information

30.

Supplementary cash flow information

Partial cash paid for investing and financing activities

Property, plant and equipment


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Purchase in property, plant and equipment		3,644,560			4,690,995			4,849,331			163,608
Add: Beginning balance of payable to contractors and equipment suppliers		1,307,459			523,962			839,983			28,339
Add: Beginning balance of lease payable		—			—			94,952			3,204
Less: Ending balance of payable to contractors and equipment suppliers		(523,962	)		(647,486	)		(878,065	)		(29,624	)
Less: Ending balance of lease payable		—			(96,006	)		(84,192	)		(2,841	)
Less: Transfer from prepaid equipment (shown as “Other non-current assets”)		—			—			(139,304	)		(4,700	)

Cash paid for acquisition of property, plant and equipment		4,428,057			4,471,465			4,682,705			157,986

Treasury stock


	2015			2016		2017		2017
	NT$000			NT$000		NT$000		US$000
Repurchase of shares		1,862,362			1,007,654		—		—
Less: Beginning balance of prepayment for the repurchase of shares		(421,003	)		—		—		—

Cash paid for purchase of treasury stock		1,441,359			1,007,654		—		—

Capital reorganization


	2015		2016			2017		2017
	NT$000		NT$000			NT$000		US$000
Net assets acquired from ChipMOS Bermuda		—		12,987,736			—		—
Less: Issuance of shares		—		(9,779,426	)		—		—

Cash consideration		—		3,208,310			—		—
Directly attributable transaction cost		—		133,311			—		—

Cash paid for capital reorganization		—		3,341,621			—		—

Disposal of a subsidiary


	2015		2016		2017			2017
	NT$000		NT$000		NT$000			US$000
Disposal of a subsidiary		—		—		2,166,151			73,082
Add: Ending balance of other payables*		—		—		64,393			2,173
Less: Cash and cash equivalents of discontinued operations		—		—		(449,331	)		(15,160	)

Cash received from disposal of a subsidiary		—		—		1,781,213			60,095

According to the Equity Interest Transfer Agreement, the Group accrued the estimated payment to investor based on the operating performance of ChipMOS Shanghai and as a result, cash received from disposal of discontinued operations amounted to NT$64,393 thousand (US$2,173 thousand) will be payable in 2018.

Reconciliation of liabilities arising from financing activities


						Non-Cash flow
	As of January 1, 2017		Cash flow*			Amortization of loans fee		As of December 31, 2017
	NT$000		NT$000			NT$000		NT$000		US$000
Long-term loans (include the current portion)		10,750,005		(1,124,699	)		16,715		9,642,021		325,305
Short-term loans		—		969,353			—		969,353		32,704
Guarantee deposits		1,404		(33	)		—		1,371		46

		10,751,409		(155,379	)		16,715		10,612,745		358,055

Above movement schedule is exclusively for continuing operations, reconciliation to the statement of cash flow should include movements from discontinued operations for proceeds from long-term and short-term loans amounted to NT$148,829 thousand (US$5,021 thousand) and NT$312,483 thousand (US$10,543 thousand), respectively.

Related party transactions

12 Months Ended

Dec. 31, 2017

Related party transactions

31.

Related party transactions

Parent and ultimate controlling party

On October 31, 2016, the Company’s former parent company, ChipMOS Bermuda, was merged with and into the Company through a share exchange with the latter being the surviving entity and ChipMOS Bermuda being the dissolved entity. After the Merger, the Company has neither a parent company nor an ultimate controlling party. The transactions between the Company and its subsidiaries were eliminated in the accompanying consolidated financial statements and were not disclosed herein. The transactions between the Group and other related parties are as follows.

Names of related parties and relationship


Name	Relationship
ChipMOS Shanghai		Associate
JMC		Associate

Significant related party transactions

(a)

Subcontracting fee


	2017		2017
	NT$000		US$000
ChipMOS Shanghai		41,183		1,389

There were no subcontracting fee to related parties for the years ended December 31, 2015 and 2016.

(b)

Disposal of property, plant and equipment

2017

Selling price

Gain on disposal

NT$000

US$000

NT$000

US$000

ChipMOS Shanghai

21,982

742

20,240

683

There were no disposal of property, plant, and equipment to related parties for the years ended December 31, 2015 and 2016.

(c)

Acquisition of financial assets

In June 2017, ChipMOS BVI participated in ChipMOS Shanghai’s increase of paid-in capital based on its shareholding amounted to NT$1,373,486 thousand (US$46,339 thousand), please refer to Note 13.

(d)

Patent licensing agreement

In May 2016, the Company and ChipMOS Shanghai entered into a patent licensing agreement. Under the agreement, ChipMOS Shanghai paid the Company a licensing fee in the aggregate total of US$2,500 thousand (amended to US$1,000 thousand in January 2017) which was accounted for as receipts in advance and long-term deferred revenue, and recognized royalty income for 10 years from the effective date. In addition, ChipMOS Shanghai shall pay the Company a running royalty for the foregoing license equivalent to 0.5% of the total revenue from the licensed products. Given that the related production lines of ChipMOS Shanghai have begun its operations in April 2017, the Company recognized royalty income henceforth. The Company recognized receipts in advance and long-term deferred revenue amounted to NT$3,018 thousand (US$102 thousand) and NT$24,898 thousand (US$840 thousand), respectively, as of December 31, 2017 and royalty income amounted to NT$2,828 thousand (US$96 thousand) for the nine months then ended.

In October 2011, ChipMOS Bermuda and ChipMOS Shanghai entered into a patent licensing agreement which has a term of 10 years starting from August 1, 2012. Under the agreement, ChipMOS Shanghai will pay ChipMOS Bermuda a royalty in the aggregate total of RMB 27,400 thousand, which was accounted as receipts in advance and payable in 40 quarterly installments of RMB 685 thousand. The rights and obligations of this agreement have been transferred to the Company on October 31, 2016. In March 2017, ChipMOS Shanghai was derecognized from the consolidated financial statements and recorded as “Investment in associates”, therefore, royalty income for the three months ended March 31, 2017 were eliminated on a consolidated basis. The Company recognized receipts in advance amounted to NT$1,039 thousand (US$35 thousand) as of December 31, 2017 and royalty income amounted to NT$9,170 thousand (US$309 thousand) for the year then ended.

Key management personnel compensation


	2015		2016		2017		2017
	NT$000		NT$000		NT$000		US$000
Short-term employee benefits		217,091		152,319		188,105		6,346
Post-employment compensation		2,249		3,335		5,622		190
Share-based payments		100,280		109,255		18,736		632

		319,620		264,909		212,463		7,168

Pledged or mortgaged assets

12 Months Ended

Dec. 31, 2017

Pledged or mortgaged assets

32.

Pledged or mortgaged assets

The Group provided certain assets as collateral mainly for long-term bank loans (Note 22) and leases, which were as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Property, plant and equipment, net (Note 14)

8,020,905

7,164,089

241,703

Other financial assets – non current

70,677

70,241

2,370

8,091,582

7,234,330

244,073

Financial instruments by category

12 Months Ended

Dec. 31, 2017

Financial instruments by category

33.

Financial instruments by category

December 31,
2016

December 31,
2017

NT$000

US$000

Financial assets

Available-for-sale financial assets

9,960

20,890

705

Loans and receivables (including cash and cash equivalents, other financial assets, accounts and notes receivable, other receivables and refundable deposits)

11,862,621

12,204,292

411,751

11,872,581

12,225,182

412,456

Financial liabilities

Financial liabilities at amortized cost (including bank loans, accounts payable, payables to contractors and equipment suppliers, lease payable, other payables and guarantee deposits)

13,579,473

14,024,304

473,155

Financial risk management and fair values of financial instruments

12 Months Ended

Dec. 31, 2017

Financial risk management and fair values of financial instruments

34.

Financial risk management and fair values of financial instruments

Financial risk management

The Group’s risk management objective is to manage the market risk, credit risk and liquidity risk related to its operating activities. The Group identifies, measures and manages the aforementioned risks based on policy and risk appetite.

The Group has established appropriate policies, procedures and internal controls for financial risk management. Before entering into significant financial transactions, due approval process by the Board of Directors must be carried out based on related protocols and internal control procedures. The Group complies with its financial risk management policies at all times.

(a)

Market risk

Market risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market prices. Market risks comprise foreign currency risk, interest rate risk, and other price risk (such as equity price risk).

Foreign currency risk

The Group’s exposure to the risk of changes in foreign exchange rates relates primarily to the Group’s operating activities (when revenue or expense is denominated in a different currency from the Group’s functional currency) and the Group’s net investments in foreign subsidiaries.

The Group applies natural hedges from using accounts receivable and accounts payable denominated in the same currency. However, this natural hedge does not concur with the requirement for hedge accounting. Furthermore, as net investments in foreign subsidiaries are for strategic purposes, they are not hedged by the Group.

The Group’s foreign currency exposure gives rise to market risks associated with exchange rate movements against the NT dollar for cash and cash equivalents, accounts receivable, other receivables, bank loans, accounts payable and other payables.

The Group’s businesses involve some non-functional currency operations. The information on the assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows:


	December 31, 2016
	Foreign currency		Exchange rate		Carrying amount (NT$000)
Financial assets
Monetary items
US$000		178,201		32.2500		5,746,982
JPY000		517,114		0.2756		142,517
Financial liabilities
Monetary items
US$000		7,802		32.2500		251,615
JPY000		550,456		0.2756		151,706


	December 31, 2017
	Foreign currency		Exchange rate		Carrying amount (NT$000)
Financial assets
Monetary items
US$000		208,066		29.7600		6,192,044
JPY000		798,254		0.2642		210,899
RMB000		167,484		4.5650		764,564
Financial liabilities
Monetary items
US$000		16,036		29.7600		477,231
JPY000		1,071,432		0.2642		283,072

The total exchange gain and the total exchange loss recognized include realized and unrealized gain and loss arising from significant foreign exchange variation on the monetary items held by the Group for the years ended December 31, 2016 and 2017 amounted to loss of NT$195,326 thousand and loss of NT$418,970 thousand (US$14,135 thousand), respectively.

The following table details the Group’s exposure at the end of the reporting period to currency risk arising from recognized monetary assets or liabilities denominated in a currency other than the functional currency of the entity to which they relate.


	December 31, 2016
	Change in exchange rate			Effect on profit (NT$000)		Effect on other comprehensive income (NT$000)
Financial assets
US$000		5	%		287,349		—
JPY000		5	%		7,126		—
Financial liabilities
US$000		5	%		12,581		—
JPY000		5	%		7,585		—


	December 31, 2017
	Change in exchange rate			Effect on profit (NT$000)		Effect on other comprehensive income (NT$000)
Financial assets
US$000		5	%		309,602		—
JPY000		5	%		10,545		—
RMB000		5	%		38,228		—
Financial liabilities
US$000		5	%		23,862		—
JPY000		5	%		14,154		—

ii)

Interest rate risk

Interest rate risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market interest rates. The Group’s exposure to the risk of changes in market interest rates relates primarily to the Group’s bank loans with floating interest rates.

The Group manages its interest rate risk by having a balanced portfolio of fixed and variable rate bank loans.

At December 31, 2017, it is estimated that a general increase or decrease of 100 basis points (1%) in interest rates, with all other variables held constant, would decrease or increase the Group’s profit by approximately NT$106,447 thousand (US$3,591 thousand) (2016: NT$108,000 thousand).

iii)

Equity price risk

The Group is exposed to equity price risk through its investments in listed equity securities classified as financial assets at fair value through profit or loss. The Group manages this exposure by maintaining a portfolio of investments with different risk and return profiles. At the reporting date, no aforesaid equity security was held and no sensitivity analysis was disclosed.

(b)

Credit risk

Credit risk is the risk that a counterparty will not meet its obligations under a financial instrument or customer contract, leading to a financial loss. The Group is exposed to credit risk from its operating activities (primarily accounts and other receivables) and from its financing activities (primarily deposits with banks and financial instruments).

Each business unit performs ongoing credit evaluation of the debtors’ financial condition according to the Group’s established policy, procedures and control relating to customer credit risk management. The Group maintains an account for allowance for doubtful receivables based upon the available facts and circumstances, historical collection and write-off experiences of all trade and other receivables which consequently minimizes the Group’s exposure to bad debts.

Credit risk from balances with banks and financial institutions is managed by the Group’s finance unit in accordance with the Group’s policy. Bank balances are held with financial institutions of good standing. The Group’s exposure to credit risk arising from the default of counter-parties is limited to the carrying amount of these instruments.

(c)

Liquidity risk

Liquidity risk is the risk that the Group will encounter difficulty in raising funds to meet commitments associated with financial instruments. The Group monitors and maintains adequate cash and banking facilities to finance the Group’s operations. See Notes 22 and 26 about the unused credit lines of the Group.

The maturity profile of the Group’s non-derivative financial liabilities as of December 31, 2016 and 2017 based on the contracted undiscounted payments is as follows:


	December 31, 2016
	£ 1 year		2 to 5 years		> 5 years		Total
	NT$000		NT$000		NT$000		NT$000
Long-term bank loans (including current portion)		1,272,266		10,110,289		—		11,382,555
Accounts payable and payables to contractors and equipment suppliers		1,375,408		—		—		1,375,408
Other payables		1,412,054		—		—		1,412,054
Lease payable		12,000		30,000		—		42,000
Guarantee deposits		—		—		1,404		1,404

		4,071,728		10,140,289		1,404		14,213,421


	December 31, 2017
	£ 1 year		2 to 5 years		> 5 years		Total		Total
	NT$000		NT$000		NT$000		NT$000		US$000
Short-term bank loans		971,813		—		—		971,813		32,787
Long-term bank loans (including current portion)		2,321,459		7,740,267		—		10,061,726		339,465
Accounts payable and payables to contractors and equipment suppliers (including related parties)		1,401,499		—		—		1,401,499		47,284
Other payables (including related parties)		1,980,218		—		—		1,980,218		66,809
Lease payable		12,266		18,266		—		30,532		1,030
Guarantee deposits		—		—		1,371		1,371		46

		6,687,255		7,758,533		1,371		14,447,159		487,421

Fair values of financial instruments

The notional amounts of financial assets and financial liabilities are assumed to approximate their fair values.

Share-based payments

12 Months Ended

Dec. 31, 2017

Share-based payments

35.

Share-based payments

Stock option plan

The former parent company of the Group, ChipMOS Bermuda adopted three option plans in 2001, 2006 and 2011 which have 2,250,000, 1,750,000 and 1,000,000 shares available for issuance, respectively. The stock option plans provide that the directors, officers, employees and consultants of ChipMOS Bermuda and its affiliates may be granted options to purchase ordinary shares of ChipMOS Bermuda at specified exercise prices. All outstanding stock options issued by ChipMOS Bermuda and received by the employees of the Company, whether vested or unvested, were settled in cash by ChipMOS Bermuda prior to the Merger in accordance with the terms of the merger agreement.

The following table illustrates the number and weighted average exercise prices (“WAEP”) of, and movements in, share options during the periods indicated:


	Ten months ended October 30, 2016			2016
	Number of options			WAEP US$
Outstanding at the beginning of the period		1,062,250			13.57
Forfeited		(25,084	)		15.35
Exercised		(97,715	)		7.21
Expired		(49,500	)		20.57
Early settled		(889,951	)		13.83

Outstanding at the end of the period		—			—

Exercisable at the end of the period		—			—

The weighted average share price at the date of exercise of these options exercised in 2016 was US$18.10.

There were no outstanding stock options as of December 31, 2016 and 2017.

Share appreciation rights (“SARs”)

The former parent company of the Group, ChipMOS Bermuda adopted three SARs plans in 2006, 2008 and 2013 which have 500,000, 750,000 and 1,000,000 rights available for issuance, respectively. The SARs plans provide that the directors, officers and employees of ChipMOS Bermuda and its affiliates may be granted cash-settled share appreciation rights. All outstanding share appreciation rights issued by ChipMOS Bermuda and received by the employees of the Company, whether vested or unvested, were settled in cash by ChipMOS Bermuda prior to the Merger in accordance with the terms of the merger agreement.

The following table illustrates the number and WAEP of, and movements in, SARs during the periods indicated:


	Ten months ended October 30, 2016			2016
	Number of rights			WAEP US$
Outstanding at the beginning of the period		588,596			14.07
Granted		37,500			19.55
Forfeited		(9,785	)		15.16
Exercised		(123,033	)		11.26
Early settled		(493,278	)		15.17

Outstanding at the end of the period		—			—

Exercisable at the end of the period		—			—

The weighted average share price at the date of exercise of these SARs exercised in 2016 was US$19.18.

The weighted average fair value of SARs granted during 2016 was US$1.34.

There were no outstanding share appreciation rights as of December 31, 2016 and 2017.

Restricted Shares

On November 12, 2014, the Board of Directors of the Company approved 2014 Restricted Stock Award Agreement which has 17,300 thousand restricted shares available for issuance. The par value and granting price of the restricted shares were NT$10 and zero, respectively. The issuance of the restricted shares was approved by the Special General Meeting of the Shareholders of the Company on December 30, 2014 and approved by the Financial Supervisory Commission ROC on June 30, 2015.

On July 14, 2015 and April 18, 2016, the Board of Directors of the Company approved to set July 21, 2015 and May 10, 2016 as the Record Date of the issuance of 15,752 thousand and 1,548 thousand restricted shares.

When the employees of ChipMOS Taiwan accomplished the following years of service and performance conditions, the received restricted shares will be vested based on the vesting ratio.


	The 1^st year	The 2^nd year	The 3^rd year
Years of service following the receipt of restricted shares	Continuous service for one year	Continuous service for two years	Continuous service for three years
Grade of performance appraisal	>=B+	>=B+	>=B+
Compliance of terms agreed by the staff and the Company	No violation	No violation	No violation
Vesting ratio of numbers of restricted shares received	30%	30%	40%

The restricted shares issued by the Company cannot be transferred during the vesting period, but voting right and dividend right are not restricted. Employees are required to return the shares but not required to return the dividends received if they resign during the vesting period. When the employees accomplish the years of service and performance conditions, the received restricted shares will be vested based on the vesting ratio.

During 2016 and 2017, the Group recognized NT$356,463 thousand and NT$123,021 thousand (US$4,151 thousand), respectively, compensation expenses in respect of the transactions of share-based payments.

Capital management

12 Months Ended

Dec. 31, 2017

Capital management

36.

Capital management

The Group manages its capital to ensure that entities in the Group will be able to continue as a going concern while maximizing the return to shareholders through the optimization of the balance between debt and equity.

The Group reviews the capital structure on an ongoing basis. As part of this review, the directors consider the cost of capital and the risks associated with each class of capital. The Group will balance its overall capital structure through the payment of dividends, new share issues and the issue of new debt or the repayment of existing debt.

The Group’s overall strategy remains unchanged from 2016.

The Group monitors capital using the liabilities to assets ratio, the percentages of which as of December 31, 2016 and 2017 were as follows:


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Total liabilities		15,048,258			15,138,993			510,762

Total assets		31,295,960			33,259,942			1,122,130

Liabilities to assets ratio		48.08	%		45.52	%		45.52	%

Compared to December 31, 2016, the liabilities to assets ratio decreased on December 31, 2017 was due to the acquisition of production equipment required.

Event after the reporting periods

12 Months Ended

Dec. 31, 2017

Event after the reporting periods

37.

Event after the reporting periods

The amendment to the Income Tax Act has been approved and promulgated in February 2018 raising the profit-seeking enterprise income tax rate from 17% to 20%, decrease the tax rate on unappropriated retained earnings from 10% to 5%, and abandon the imputation tax credit account effective from fiscal year starting on January 1, 2018.

In January 2018, ChipMOS BVI participated in ChipMOS Shanghai’s increase of paid-in capital based on its shareholding amounted to NT$794,694 thousand (US$26,812 thousand).

On March 15, 2018, by considering the adjustment of capital structure and increasing of return of equity, the Company’s Board of Directors approved to reduce and return capital stock to shareholders at $1.5 per share. The proposal will be further discussed in shareholders’ meeting.

Financial Statements Schedule: Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Financial Statements Schedule: Valuation and Qualifying Accounts

39.

Financial Statements Schedule: Valuation and Qualifying Accounts


	January 1		Additions charged to expense		Deduction / Write-offs			Exchange difference on translations of foreign financial statement			Non-current assets held for sale			December 31
	NT$000		NT$000		NT$000			NT$000			NT$000			NT$000
Year of 2015 :

Allowance for impairment of property, plant and equipment		2,110,362		1,478		(85,351	)		(31,774	)		—			1,994,715

Allowance for impairment of obsolescence and decline in market value of inventories		82,582		12,717		(151	)		(112	)		—			95,036

Year of 2016 :

Allowance for impairment of property, plant and equipment		1,994,715		8,198		(45,319	)		(118,046	)		(1,480,278	)		359,270

Allowance for impairment of obsolescence and decline in market value of inventories		95,036		66,894		—			(557	)		(6,532	)		154,841

Year of 2017 :

Allowance for impairment of property, plant and equipment		359,270		956		(39,771	)		—			—			320,455

Allowance for impairment of obsolescence and decline in market value of inventories		154,841		—		(101,127	)		—			—			53,714

Basis of preparation of financial statements and principal accounting policies (Policies)

12 Months Ended

Dec. 31, 2017

New and amended standards adopted by the group

Basis of preparation

Basis of preparation

The consolidated financial statements have been prepared on a historical cost basis, except for the defined benefit pension plans – plan assets measured at fair value.

These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency.

New and amended standards adopted by the group

Amendments to IAS 7 “Disclosure Initiative”

New and revised International Financial Reporting Standards not yet adopted

New and revised International Financial Reporting Standards not yet adopted


New Standards, Interpretations and Amendments	Effective date by IASB
IFRS 9, “Financial Instruments”		January 1, 2018
IFRS 15, “Revenue from Contracts with Customers”		January 1, 2018
IFRS 16, “Leases”		January 1, 2019

(a)

Financial assets at fair value through other comprehensive income

(b)

Financial assets at fair value through profit or loss

(c)

Provision for impairment

(d)

Revenue recognition of customized products

(e)

Presentation of contract assets and contract liabilities

(f)

Recognition of deferred tax

Other Amendments to IFRSs not listed above are not expected to have a material impact on the entity in the current or future reporting periods and on foreseeable future transactions.

Basis of consolidation

Basis of consolidation

Subsidiaries included in the consolidated financial statements:

Percentage of
Ownership (%)

December 31,

Name of investor

Name of investee

Main businesses

Location

2016

2017

Note

The Company

ChipMOS U.S.A., Inc. (“ChipMOS USA”)

Research, development and marketing of semiconductors, circuits, and electronic related products

San Jose, USA

100

The Company

ChipMOS BVI

Holding company

British Virgin Islands

100

ChipMOS BVI

ChipMOS Shanghai

Semiconductor assembling and testing services

People’s Republic of China (“PRC”)

100

—

Significant judgments and estimates

Significant judgments and estimates

Management has considered the development, selection and disclosure of the Group’s critical accounting policies and estimates.

Judgments

Provisions – deficiency compensation

Estimates and assumptions

Revenue recognition

Causes and effects of accounting change


	2016			2017			2018			2019
	NT$000			NT$000			NT$000			NT$000
Decrease in depreciation expenses		(119,737	)		(605,259	)		(389,972	)		(164,824	)

Property, plant and equipment and depreciation

Property, plant and equipment and depreciation

Property, plant and equipment are stated at cost, less provision for depreciation and impairment losses, if any.

Depreciation is provided on the straight-line method, based on the estimated useful life of the individual assets, as follows:


Buildings		6 to 51 years
Machinery and equipment		2 to 8 years
Tools		2 to 3 years
Other equipment		2 to 6 years

Impairment of non-financial assets

Impairment of non-financial assets

Inventories

Inventories

Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale.

Non-current assets held for sale

Non-current assets held for sale

Investments and other financial assets

Investments and other financial assets

Initial recognition and measurement

Effective interest method

Income is recognized on an effective interest basis for debt instruments.

Subsequent measurement

The subsequent measurement of financial assets depends on their classification as follows:

Financial assets at fair value through profit or loss

Financial assets at FVTPL include financial assets held for trading and those designated as at FVTPL upon initial recognition.

A financial asset other than a financial asset held for trading may be designated as at FVTPL upon initial recognition if:

•

such designation eliminates or significantly reduces a measurement or recognition inconsistency that would otherwise arise; or

•

There were no financial assets at FVTPL at the end of the reporting periods.

Loans and receivables

Available-for-sale financial investments

Impairment of financial assets

Impairment of financial assets

Financial assets carried at amortized cost

Available-for-sale financial assets

Derecognition of financial assets

Derecognition of financial assets

•

the rights to receive cash flows from the asset have expired; or

•

Investments in associates

Investments in associates

(a)

(b)

Financial liabilities

Financial liabilities

Initial recognition and measurement

All financial liabilities are recognized initially at fair value and, in the case of loans and borrowings, net of directly attributable transaction costs.

The Group’s financial liabilities include bank loans, accounts payable and other monetary liabilities.

Subsequent measurement

The subsequent measurement of financial liabilities depends on their classification as follows:

Loans and borrowings

Notes and accounts payable

Derecognition of financial liabilities

Derecognition of financial liabilities

Dividends

Dividends

Dividends are recommended by the Board of Directors to the Shareholders’ approval pursuant to the Company’s Article of Incorporation.

Operating lease charges

Operating lease charges

Treasury stock

Treasury stock

Provisions

Provisions

Foreign currency translation

Foreign currency translation

Revenue recognition

Revenue recognition

Interest income

Research and development costs

Research and development costs

Research and development costs that do not meet the criteria of internally generated intangible assets of IAS 38 “Intangible Assets” are expensed in the period in which it is incurred.

Borrowing costs

Borrowing costs

Pension and other post-employment benefits

Pension and other post-employment benefits

Share-based payments

Share-based payments

Equity-settled transactions

The cost of equity-settled transactions is determined by the fair value at the date when the grant is made using an appropriate valuation model.

Cash-settled transactions

Restricted shares

Restricted shares issued to employees are measured at the fair value of the equity instruments granted at the grant date, and are recognized as compensation cost over the vesting period.

For restricted shares where employees do not need to pay to acquire those shares, if the employees who resign during the vesting period, the Group will recover and retire those shares at no cost.

Income tax

Income tax

Deferred tax liabilities are recognized for all taxable temporary differences, except:

•

extent that it has become probable that sufficient taxable profit will be available to allow all or part of the deferred tax asset to be recovered.

Cash and cash equivalents

aa)

Cash and cash equivalents

Related parties

bb)

Related parties

(a)

A person, or a close member of that person’s family, is related to the Group if that person:

(i)

has control or joint control over the Group;

(ii)

has significant influence over the Group; or

(iii)

is a member of key management personnel of the Group or the Group’s parent.

(b)

An entity is related to the Group if any of the following conditions applies:

(i)

The entity and the Group are members of the same group.

(ii)

One entity is an associate or joint venture of the other entity (or an associate or joint venture of a member of a group of which the other entity is a member).

(iii)

The entity and the Group are joint ventures of the same third party.

(iv)

One entity is a joint venture of a third entity and the other entity is an associate of the third entity.

(v)

The entity is a post-employment benefit plan for the benefit of employees of either the Group or an entity related to the Group.

(vi)

The entity is controlled or jointly controlled by a person identified in (a).

(vii)

A person identified in (a)(i) has significant influence over the entity or is a member of the key management personnel of the entity (or of a parent of the entity).

Subsidiaries

cc)

Subsidiaries

•

the contractual arrangement with the other vote holders of the investee;

•

rights arising from other contractual arrangements; and

•

the Group’s voting rights and potential voting rights

Fair value measurement

dd)

Fair value measurement

Level 1 – based on quoted prices (unadjusted) in active markets for identical assets or liabilities

Level 2 – based on valuation techniques for which the lowest level input that is significant to the fair value measurement is observable, either directly or indirectly

Level 3 – based on valuation techniques for which the lowest level input that is significant to the fair value measurement is unobservable

Capital reorganization

ee)

Capital reorganization

Basis of preparation of financial statements and principal accounting policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Ownership Interests in Subsidiaries

Subsidiaries included in the consolidated financial statements:

Percentage of
Ownership (%)

December 31,

Name of investor

Name of investee

Main businesses

Location

2016

2017

Note

The Company

ChipMOS U.S.A., Inc. (“ChipMOS USA”)

Research, development and marketing of semiconductors, circuits, and electronic related products

San Jose, USA

100

The Company

ChipMOS BVI

Holding company

British Virgin Islands

100

ChipMOS BVI

ChipMOS Shanghai

Semiconductor assembling and testing services

People’s Republic of China (“PRC”)

100

—

Impact on Depreciation Expenses of Current and Future Periods due to Change in Estimated Useful Lives of Certain Properties and Equipment

The impact on depreciation expenses of current and future periods were expected as follows:


	2016			2017			2018			2019
	NT$000			NT$000			NT$000			NT$000
Decrease in depreciation expenses		(119,737	)		(605,259	)		(389,972	)		(164,824	)

Estimated Useful Life for Depreciation of Individual Assets

Depreciation is provided on the straight-line method, based on the estimated useful life of the individual assets, as follows:


Buildings		6 to 51 years
Machinery and equipment		2 to 8 years
Tools		2 to 3 years
Other equipment		2 to 6 years

Segment Information (Tables)

12 Months Ended

Dec. 31, 2017

Financial Segment Information for Operating Segments


	2015
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000
Revenue
External customers		4,546,394			5,525,582			5,396,001			3,369,112			—			—			18,837,089			1,032,302
Inter-segment		172,264			528			—			—			44,577			(217,369	)		—			—

Total revenue		4,718,658			5,526,110			5,396,001			3,369,112			44,577			(217,369	)		18,837,089			1,032,302

Operating profit (loss)		1,203,169			117,127			1,354,398			28,605			(47,191	)		(7,681	)		2,648,427			(61,214	)
Depreciation and amortization		(646,545	)		(550,819	)		(1,157,809	)		(548,234	)		(357	)		543			(2,903,221	)		(118,702	)
Interest income		—			—			—			—			60,552			(1,690	)		58,862			9,421
Interest expense		—			—			—			—			(128,311	)		1,690			(126,621	)		(414	)
Share of profit of associates		—			—			—			—			25,346			5,923			31,269			—
Purchase of property, plant and equipment		796,964			895,767			1,366,389			589,615			2,477			(6,652	)		3,644,560			—


	2016
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000
Revenue
External customers		4,587,054			5,880,780			4,920,302			2,999,457			—			—			18,387,593			1,005,166
Inter-segment		—			1,103			—			510			41,670			(43,283	)		—			—

Total revenue		4,587,054			5,881,883			4,920,302			2,999,967			41,670			(43,283	)		18,387,593			1,005,166

Operating profit (loss)		1,346,874			143,220			963,698			(341,356	)		(82,331	)		(31,530	)		1,998,575			(146,263	)
Depreciation and amortization		(664,026	)		(635,481	)		(1,167,908	)		(622,412	)		(565	)		488			(3,089,904	)		(141,375	)
Interest income		—			—			—			—			51,756			(13,202	)		38,554			3,753
Interest expense		—			—			—			—			(144,545	)		—			(144,545	)		(606	)
Share of profit (loss) of associates		—			—			—			—			(128,866	)		157,790			28,924			—
Purchase of property, plant and equipment		771,500			554,162			910,457			887,144			49			—			3,123,312			1,567,683


	2017
	Testing			Assembly			LCDD			Bumping			Others			Elimination			Total continuing operations			Total continuing operations			Discontinued operations			Discontinued operations
	NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			US$000			NT$000			US$000
Revenue
External customers		4,838,246			5,259,281			4,789,869			3,053,459			—			—			17,940,855			605,292			227,095			7,662
Inter-segment		—			—			247			—			35,808			(36,055	)		—			—			—			—

Total revenue		4,838,246			5,259,281			4,790,116			3,053,459			35,808			(36,055	)		17,940,855			605,292			227,095			7,662

Operating profit (loss)		1,448,939			(55,198	)		1,285,495			(336,123	)		(100,545	)		(2,687	)		2,239,881			75,570			(25,394	)		(857	)
Depreciation and amortization		(673,393	)		(597,500	)		(1,048,587	)		(579,605	)		(503	)		310			(2,899,278	)		(97,816	)		—			—
Interest income		—			—			—			—			53,123			—			53,123			1,792			464			16
Interest expense		—			—			—			—			(190,425	)		—			(190,425	)		(6,425	)		(2,414	)		(81	)
Share of profit (loss) of associates		—			—			—			—			1,347,851			(1,527,342	)		(179,491	)		(6,056	)		—			—
Purchase of property, plant and equipment		836,894			655,879			2,615,153			594,765			—			—			4,702,691			158,660			—			—

Geographic Information of Revenue

Geographic information of revenue:


	2015		2016		2017		2017
	NT$000		NT$000		NT$000		US$000
Area
ROC		13,529,739		12,728,014		13,152,419		443,739
Japan		986,403		1,855,674		2,257,296		76,157
Singapore		2,928,591		3,087,835		1,798,585		60,681
Others		1,392,356		716,070		732,555		24,715

		18,837,089		18,387,593		17,940,855		605,292

Net Revenue from Customers Representing at Least 10% of Total Revenue

Net revenue from customers representing at least 10% of the total revenue:


	2015				2016				2017				2017
	Amount		%		Amount		%		Amount		%		Amount
	NT$000				NT$000				NT$000				US$000
Customers
Customer A		4,307,855		23		3,370,285		18		3,434,873		19		115,886
Customer K		2,386,975		13		2,633,431		14		2,742,882		15		92,540
Customer I		2,935,820		16		3,085,190		17		1,798,111		10		60,665
Customer C		1,761,049		9		1,870,675		10		1,530,209		9		51,626

The revenue generated from the above customers is mainly from the segments of Assembly and LCDD.

Operating costs and expenses (Tables)

12 Months Ended

Dec. 31, 2017

Analysis of income and expense [abstract]

Summary of Operating Costs and Expenses


	2015		2016			2017		2017
	NT$000		NT$000			NT$000		US$000
Change of finished goods and work in process		7,899		(19,498	)		31,977		1,079
Consumption of raw materials and supplies		3,271,581		3,346,540			3,036,350		102,441
Employee benefit expenses		5,358,962		5,317,125			5,895,778		198,913
Depreciation and amortization		2,903,221		3,089,904			2,899,278		97,816
Other expenses		4,752,050		4,745,253			4,530,425		152,848

Total operating costs and expenses		16,293,713		16,479,324			16,393,808		553,097

Employee benefit expenses
Salaries		4,300,550		4,126,203			4,874,709		164,464
Labor and health insurance		355,331		351,232			390,788		13,184
Pension		179,665		183,293			198,502		6,697
Share-based payments		207,242		356,463			123,021		4,151
Other personnel expenses		316,174		299,934			308,758		10,417

		5,358,962		5,317,125			5,895,778		198,913

Other operating income (expenses), net (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Other Operating Income (Expenses), Net


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Gain on disposal of property, plant and equipment, net		1,562			2,575			132,777			4,480
Impairment on property, plant and equipment		(1,460	)		(8,198	)		(956	)		(32	)
Gain on disposal of scrapped materials		31,870			30,476			27,940			943
Gain on disposal of items purchased on behalf of others		22,893			48,812			26,417			891
Royalty income		—			—			11,998			405
Insurance compensation income		—			7,033			486,858			16,426
Others		50,186			9,608			7,800			262

		105,051			90,306			692,834			23,375

Finance costs (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Finance Costs


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Interest on bank loans		146,003			157,254			208,486			7,034
Interest on lease payable		—			212			708			24
Less: Amounts capitalized in qualifying assets		(19,382	)		(12,921	)		(18,769	)		(633	)

		126,621			144,545			190,425			6,425
Finance expense		15,890			34,571			26,858			906

		142,511			179,116			217,283			7,331

Other non-operating income (expenses), net (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Other Non-operating Income (Expenses), Net


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Interest income		58,862			38,554			53,123			1,792
Foreign exchange gains (losses), net		241,983			(195,326	)		(418,970	)		(14,135	)
Impairment of available-for-sale financial assets		(8,584	)		—			—			—
Gain on disposal of financial assets at fair value through profit or loss		11,483			621			637			22
Gain on disposal of long-term investment in associates		—			—			16,929			571
Share of profit (loss) of associates		31,269			28,924			(179,491	)		(6,056	)
Reimbursement of ADSs service charge		—			—			23,707			800
Others		5,127			8,203			13,883			468

		340,140			(119,024	)		(490,182	)		(16,538	)

Income tax expense (Tables)

12 Months Ended

Dec. 31, 2017

Major Components of Income Tax Expense

The major components of income tax expense for the years ended December 31, 2015, 2016 and 2017 are:


	2015			2016			2017		2017
	NT$000			NT$000			NT$000		US$000
Current income tax:
Current income tax on profits for the period		720,461			331,144			125,376		4,230
Income tax (benefit) on unappropriated retained earnings		198,157			(174,930	)		246,684		8,322
Prior year income tax (over) under estimation		(1,732	)		4,527			67,885		2,290

Total current income tax		916,886			160,741			439,945		14,842

Deferred income tax:
Relating to origination and reversal of temporary differences		18,969			16,379			110,542		3,730

Total deferred income tax		18,969			16,379			110,542		3,730

Income tax expense reported in the consolidated statements of comprehensive income		935,855			177,120			550,487		18,572

Deferred Tax Charged to Other Comprehensive Income

Deferred tax charged to other comprehensive income:

2015

2016

2017

NT$000

US$000

Remeasurement of defined benefit obligations

(7,099

)

(7,375

)

8,642

292

Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax

Reconciliation of income tax expense and the accounting profit before income tax:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Tax calculated based on profit before tax and statutory tax rate		462,692			214,550			566,649			19,118
Expenses disallowed (added) by tax regulations		5,692			(2,190	)		10,185			344
Temporary difference not recognized as deferred tax assets		6,522			1,306			(85,168	)		(2,873	)
Tax exempted (income) expenses by tax regulation		(13,483	)		12,057			(256,788	)		(8,664	)
Taxable loss not recognized as deferred tax assets		25,737			54,012			—			—
Effect of different tax rates in countries in which the Group operates		3,100			10,451			1,040			35
Withholding tax		249,170			57,337			—			—
Prior year income tax (over) under estimation		(1,732	)		4,527			67,885			2,290
Income tax (benefit) on unappropriated retained earnings		198,157			(174,930	)		246,684			8,322

Income tax expense reported in the consolidated statements of comprehensive income		935,855			177,120			550,487			18,572

Details of Deferred Tax Assets (Liabilities)

The details of deferred tax assets (liabilities) are as follows:


	January 1,			Profit and (loss)			Other comprehensive income			December 31,			December 31,
	NT$000			NT$000			NT$000			NT$000			US$000
Year of 2016
Deferred tax assets
Unrealized exchange losses		(5,843	)		5,843			—			—
Inventories		14,823			11,501			—			26,324
Property, plant and equipment		3,672			77,197			—			80,869
Deferred income		50,423			(9,129	)		—			41,294
Provisions		16,473			(5,241	)		—			11,232
Net defined benefit liability, non-current		86,719			(4,007	)		7,375			90,087

Deferred tax assets		166,267			76,164			7,375			249,806

Deferred tax liabilities
Unrealized exchange gains		—			(14,155	)		—			(14,155	)
Property, plant and equipment		—			(78,388	)		—			(78,388	)

Deferred tax liabilities		—			(92,543	)		—			(92,543	)

Year of 2017
Deferred tax assets
Unrealized exchange losses		—			8,167			—			8,167			276
Inventories		26,324			(17,192	)		—			9,132			308
Property, plant and equipment		80,869			(25,375	)		—			55,494			1,872
Deferred income		41,294			(1,809	)		—			39,485			1,332
Provisions		11,232			10,411			—			21,643			730
Net defined benefit liability, non-current		90,087			(2,994	)		(8,642	)		78,451			2,647

Deferred tax assets		249,806			(28,792	)		(8,642	)		212,372			7,165

Deferred tax liabilities
Unrealized exchange gains		(14,155	)		14,155			—			—			—
Property, plant and equipment		(78,388	)		(95,905	)		—			(174,293	)		(5,880	)

Deferred tax liabilities		(92,543	)		(81,750	)		—			(174,293	)		(5,880	)

Earnings per share ("EPS") (Tables)

12 Months Ended

Dec. 31, 2017

Income and Share Data Used in Basic and Diluted EPS Computations

The following reflects the income and share data used in the basic and diluted EPS computations:


	2015
	Amount after income tax			Weighted average number of ordinary shares outstanding*		Earnings per share
Basic earnings per share	NT$000			in thousands		NT$
Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		2,164,557					2.47
- Discontinued operations		(34,233	)				(0.04	)

Equity holders of the Company		2,130,324					2.43
Predecessors’ interests		(291,429	)				(0.33	)

	1,838,895			877,402		2.10

Diluted earnings per share
Employees’ bonuses					10,867
Restricted shares					27

Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		2,164,557					2.44
- Discontinued operations		(34,233	)				(0.04	)

Equity holders of the Company		2,130,324					2.40
Predecessors’ interests		(291,429	)				(0.33	)

	1,838,895			888,296		2.07


	2016
	Amount after income tax			Weighted average number of ordinary shares outstanding*		Earnings per share
Basic earnings per share	NT$000			In thousands		NT$
Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		1,829,327					2.13
- Discontinued operations		(122,105	)				(0.14	)

Equity holders of the Company		1,707,222					1.99
Predecessors’ interests		(306,012	)				(0.35	)

	1,401,210			859,644		1.64

Diluted earnings per share
Employees’ bonuses					3,035
Restricted shares					4,122

Profit (loss) attributable to:
Equity holders of the Company
- Continuing operations		1,829,327					2.11
- Discontinued operations		(122,105	)				(0.14	)

Equity holders of the Company		1,707,222					1.97
Predecessors’ interests		(306,012	)				(0.35	)

	1,401,210			866,801		1.62

2017

Amount
after income
tax

Weighted average
number of ordinary
shares outstanding

Earnings
per share

Basic earnings per share

NT$000

In thousands

NT$

US$

Profit attributable to:

Equity holders of the Company

- Continuing operations

981,929

1.16

0.04

- Discontinued operations

1,814,953

2.14

0.07

2,796,882

846,686

3.30

0.11

Diluted earnings per share

Employees’ bonuses

14,034

Restricted shares

5,075

Profit attributable to:

Equity holders of the Company

- Continuing operations

981,929

1.13

0.04

- Discontinued operations

1,814,953

2.10

0.07

2,796,882

865,795

3.23

0.11

The weighted average number of shares takes into account the weighted average effect of changes in treasury stock transaction during the year.

Available-for-sale financial assets (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Available-for-Sale Financial Assets


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Unlisted equity investments, at cost		79,880			49,474			1,669
Less: Allowance for impairment losses		(69,920	)		(28,584	)		(964	)

		9,960			20,890			705

Investment in associates (Tables)

12 Months Ended

Dec. 31, 2017

Details of Investment in Associates

Details of investment in associates are as follows:

Country of
incorporation
and business

Measurement
method

December 31, 2016

December 31, 2017

Investee company

Carrying
amount

Ownership

Carrying
amount

Ownership

NT$000

US$000

JMC ELECTRONICS CO., LTD. (“JMC”)

Kaohsiung
Taiwan

Equity
method

369,329

21.22

373,276

12,593

19.10

ChipMOS Shanghai

Shanghai

PRC

Equity
method

—

3,060,056

103,241

45.02

Summarized Financial Information for Investment in Material Associates

The tables below provide summarized financial information for the investment in associates that are material to the Group.

Statements of financial position


	JMC
	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Current assets		904,571			833,914			28,134
Non-current assets		876,314			1,161,620			39,191
Current liabilities		(258,513	)		(284,580	)		(9,601	)
Non-current liabilities		(2,491	)		(1,756	)		(59	)

Total net assets		1,519,881			1,709,198			57,665

Group’s share		322,509			326,456			11,014
Goodwill		46,820			46,820			1,579

Carrying amount		369,329			373,276			12,593

Statements of financial position


	ChipMOS Shanghai
	December 31, 2017			December 31, 2017
	NT$000			US$000
Current assets		3,380,641			114,056
Non-current assets		2,766,839			93,348
Current liabilities		(460,054	)		(15,521	)
Non-current liabilities		(489,097	)		(16,501	)

Total net assets		5,198,329			175,382

Group’s share		2,340,506			78,965
Depreciable assets		703,536			23,736
Goodwill		22,118			746
Inter-company transactions and amortization		(6,104	)		(206	)

Carrying amount		3,060,056			103,241

Statements of comprehensive income

JMC

Year ended December 31,

2016

2017

NT$000

US$000

Revenue

1,667,761

1,322,928

44,633

Profit for the year from continuing operations

136,303

4,414

149

Other comprehensive income, net of income tax

(627

)

2,903

Total comprehensive income

135,676

7,317

247

Dividend received from the associate

5,730

14,325

483


	ChipMOS Shanghai
	Year ended December 31,
	2017			2017
	NT$000			US$000
Revenue		1,141,415			38,509

Loss for the year from continuing operations		(348,472	)		(11,757	)
Other comprehensive income, net of income tax		—			—

Total comprehensive income		(348,472	)		(11,757	)

Dividend received from the associate		—			—

Property, plant and equipment, net (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Property, Plant and Equipment, Net


	Land		Buildings			Machinery and equipment			Tools			Other equipment			Construction in progress and equipment to be inspected			Total			Total
	NT$000		NT$000			NT$000			NT$000			NT$000			NT$000			NT$000			US$000
January 1, 2016
Cost		452,738		10,700,236			45,945,380			3,673,636			3,047,001			826,103			64,645,094
Accumulated depreciation and impairment		—		(5,863,556	)		(38,602,675	)		(3,323,862	)		(2,643,441	)		—			(50,433,534	)

		452,738		4,836,680			7,342,705			349,774			403,560			826,103			14,211,560

January 1, 2016		452,738		4,836,680			7,342,705			349,774			403,560			826,103			14,211,560
Additions		—		255,916			934,913			358,413			351,850			2,789,903			4,690,995
Disposals		—		(51	)		(8,624	)		—			(351	)		—			(9,026	)
Reclassifications		—		372,448			1,509,798			22,882			37,373			(1,942,501	)		—
Depreciation expenses		—		(631,233	)		(2,188,976	)		(201,755	)		(206,477	)		—			(3,228,441	)
Impairment losses		—		—			—			—			(8,198	)		—			(8,198	)
Exchange adjustments		—		(45,814	)		(18,196	)		(4,871	)		(11,134	)		(45,689	)		(125,704	)

December 31, 2016		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186

December 31, 2016
Cost		452,738		11,183,278			47,002,228			3,999,894			3,353,413			1,627,816			67,619,367
Accumulated depreciation and impairment		—		(6,395,332	)		(39,430,608	)		(3,475,451	)		(2,786,790	)		—			(52,088,181	)

		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186
Less: Property, plant and equipment classified as held for sale		—		(710,191	)		(433,688	)		(90,460	)		(168,314	)		(631,315	)		(2,033,968	)

		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218

January 1, 2017
Cost		452,738		11,183,278			47,002,228			3,999,894			3,353,413			1,627,816			67,619,367			2,281,355
Accumulated depreciation and impairment		—		(6,395,332	)		(39,430,608	)		(3,475,451	)		(2,786,790	)		—			(52,088,181	)		(1,757,361	)

		452,738		4,787,946			7,571,620			524,443			566,623			1,627,816			15,531,186			523,994
Less: Property, plant and equipment classified as held for sale		—		(710,191	)		(433,688	)		(90,460	)		(168,314	)		(631,315	)		(2,033,968	)		(68,622	)

		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218			455,372

January 1, 2017		452,738		4,077,755			7,137,932			433,983			398,309			996,501			13,497,218			455,372
Additions		—		211,098			2,007,767			571,601			195,957			1,716,268			4,702,691			158,660
Disposals		—		—			(30,066	)		(2,302	)		(1,865	)		—			(34,233	)		(1,155	)
Reclassifications		—		141,400			1,535,619			44,882			22,149			(1,744,050	)		—			—
Depreciation expenses		—		(511,167	)		(1,837,482	)		(357,695	)		(192,934	)		—			(2,899,278	)		(97,816	)
Impairment losses		—		—			—			—			(956	)		—			(956	)		(32	)
Exchange adjustments		—		—			(43	)		—			(88	)		—			(131	)		(5	)

December 31, 2017		452,738		3,919,086			8,813,727			690,469			420,572			968,719			15,265,311			515,024

December 31, 2017
Cost		452,738		9,809,970			45,778,207			4,004,703			2,624,083			968,719			63,638,420			2,147,045
Accumulated depreciation and impairment		—		(5,890,884	)		(36,964,480	)		(3,314,234	)		(2,203,511	)		—			(48,373,109	)		(1,632,021	)

		452,738		3,919,086			8,813,727			690,469			420,572			968,719			15,265,311			515,024

Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment

As of December 31, 2016 and 2017, certain of the above property, plant and equipment were pledged as collateral for long-term bank loans (Notes 32).

2016

2017

NT$000

US$000

Capitalization interest

13,435

18,769

633

Capitalization interest rate applied

1.7456%~3.6166%

1.7624%

Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Cost of Inventories Recognized as an Expense

Summary of Inventories


	December 31, 2016
	Cost		Allowance for impairment losses			Carrying amount
	NT$000		NT$000			NT$000
Raw materials		1,787,810		(140,463	)		1,647,347
Work in process		190,823		(14,203	)		176,620
Finished goods		54,190		(175	)		54,015

		2,032,823		(154,841	)		1,877,982


	December 31, 2017
	Cost		Allowance for impairment losses			Carrying amount
	NT$000		NT$000			NT$000		US$000
Raw materials		1,769,917		(49,183	)		1,720,734		58,054
Work in process		180,252		(4,163	)		176,089		5,941
Finished goods		32,784		(368	)		32,416		1,094

		1,982,953		(53,714	)		1,929,239		65,089

The cost of inventories recognized as an expense for the year:


	2016		2017			2017
	NT$000		NT$000			US$000
Cost of revenue		14,670,711		14,766,555			498,197
Loss on abandonment		7,098		38,301			1,292
Allowance for (reversal of) inventory valuation and obsolescence loss		67,663		(101,127	)		(3,412	)

		14,745,472		14,703,729			496,077

Accounts and notes and other receivables (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Accounts and Notes and Other Receivables


	December 31, 2016			December 31, 2017		December 31, 2017
	NT$000			NT$000		US$000
Accounts receivable		4,138,580			4,013,705		135,415
Notes receivable		1,753			2,029		69
Less: Allowance for impairment losses		(87	)		—		—

		4,140,246			4,015,734		135,484

Other receivables		57,411			56,716		1,914
Less: Allowance for impairment losses		—			—		—

		57,411			56,716		1,914

		4,197,657			4,072,450		137,398

Movements in Allowance for Impairment of Accounts and Other Receivables

The movements in allowance for impairment of accounts and other receivables during the years are as follows:


	Accounts receivable			Other receivables
	NT$000			NT$000
January 1, 2016		—			—
Impairment losses recognized		87			—

December 31, 2016		87			—
Reversal of allowance for impairment losses		(87	)		—

December 31, 2017		—			—

December 31, 2017 (US$000)		—			—

Ageing of Accounts Receivable which are Past Due but not Impaired

Ageing of accounts receivable which are past due but not impaired is as follows:


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
£ 1 month		24,141		10,482		354
1 – 2 months		728		477		16
2 – 3 months		183		426		14
3 – 4 months		245		1,431		48
> 4 months		2,013		3,056		103

		27,310		15,872		535

Cash and cash equivalents (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Cash and Cash Equivalents


	December 31, 2016			December 31, 2017		December 31, 2017
	NT$000			NT$000		US$000
Short-term deposits		3,854,354			3,883,614		131,026
Cash		525			470		16
Cash at banks		4,106,384			4,151,630		140,068

		7,961,263			8,035,714		271,110
Less: Cash and cash equivalents classified as non-current assets held for sale		(389,897	)		—		—

		7,571,366			8,035,714		271,110

Non-current assets held for sale and discontinued operations (Tables) - Discontinued operations: ChipMOS Shanghai [member]

12 Months Ended

Dec. 31, 2017

Cash Flow Information of Discontinued Operations

The cash flow information of the discontinued operations is as follows:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Net cash generated from (used in) operating activities		1,072,628			(1,109,029	)		(109,079	)		(3,680	)
Net cash used in investing activities		(205,292	)		(1,331,564	)		(272,925	)		(9,208	)
Net cash generated from (used in) financing activities		(91,234	)		1,463,664			461,312			15,564
Effect of foreign exchange rate changes		(18,636	)		(61,336	)		(19,874	)		(671	)

Net increase (decrease) in cash and cash equivalents		757,466			(1,038,265	)		59,434			2,005

Assets, Liabilities and Equity of Disposal Group Classified as Held for Sale

Assets of disposal group classified as non-current assets held for sale:


	December 31,
	2016
	NT$000
Cash and cash equivalents		389,897
Accounts receivable		230,523
Other receivables		202,909
Inventories		136,842
Prepayments		15,943
Other current financial assets		1,193
Property, plant and equipment, net		2,033,968
Refundable deposits		113
Prepaid rent – non-current portion		82,291
Other non-current assets		11,392

		3,105,071

Liabilities of disposal group classified as liabilities directly related to non-current assets held for sale :


	December 31,
	2016
	NT$000
Accounts payable		98,973
Other payables		177,178
Receipts in advance		6,687
Bank loans – current portion		7,614
Lease payable – current		27,702
Other current liabilities		34,276
Bank loans – non-current		106,461
Lease payable – non-current		27,702
Long-term deferred revenue		100,395
Guarantee deposits		651

		587,639

Equity of disposal group classified as amounts recognized in other comprehensive income and accumulated in equity relating to non-current assets held for sale :


	December 31,
	2016
	NT$000
Foreign currency translation reserve		287,645

Cumulative Income or Expense Recognized in Other Comprehensive Income Relating to Disposal Group Classified as Held for Sale

Cumulative income or expense recognized in other comprehensive income relating to disposal group classified as held for sale:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Exchange differences on translation of foreign operations		(27,893	)		(195,972	)		(287,645	)		(9,705	)

Results of Discontinued Operations

The results of discontinued operations are as follows:


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Revenue		1,032,302			1,005,166			227,095			7,662
Cost of revenue		(1,050,075	)		(986,004	)		(195,078	)		(6,582	)
Operating expenses		(51,910	)		(179,178	)		(58,840	)		(1,985	)
Other operating income (expenses), net		8,469			13,753			1,429			48
Non-operating income (expenses), net		26,981			24,158			(2,887	)		(97	)

Loss from discontinued operations before income tax		(34,233	)		(122,105	)		(28,281	)		(954	)
Income tax expense		—			—			—			—

Loss from discontinued operations after income tax		(34,233	)		(122,105	)		(28,281	)		(954	)
Gain on disposal of discontinued operations		—			—			1,843,234			62,187

Profit (loss) from discontinued operations		(34,233	)		(122,105	)		1,814,953			61,233

Discontinued operations’ revenue is mainly from the segments of testing and assembly.

Issued capital (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Issued Capital

December 31,
2015

December 31,
2016

December 31,
2017

in thousands

Authorized shares

Ordinary shares

970,000

1,450,000

970,000

December 31,
2015

December 31,
2016

December 31,
2017

in thousands

Ordinary shares issued and fully paid

Ordinary shares

896,206

886,966

886,297

Issued capital (NT$000)

8,962,066

8,869,663

8,862,971

(US$299,021
thousand

)

Movement of Ordinary Shares Issued

The movement of ordinary shares issued is set out below:


	2015			2016			2017
	in thousands			in thousands			in thousands
January 1		864,619			896,206			886,966
Transactions with non-controlling interests (Note 28)		35,932			—			—
Restricted shares		15,752			435			—
Unearned restricted shares – cancelled		(97	)		—			(669	)
Share cancellation		(20,000	)		—			—
Issuance of ordinary shares for capital reorganization (Note 29)		—			512,405			—
Cancellation of ordinary shares from capital reorganization (Note 29)		—			(522,080	)		—

December 31		896,206			886,966			886,297

Capital surplus and retained earnings (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Capital Surplus

Details of the Group’s capital surplus are set out below:


	December 31, 2015		December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		NT$000		US$000
Share premium		2,501,767		6,473,471		5,873,743		198,169
Share-based payment		849,482		—		—		—
Restricted shares		397,296		408,051		390,401		13,171
Others		7,304		7,304		7,304		247

		3,755,849		6,888,826		6,271,448		211,587

Summary of Distribution Towards Legal Reserve and Cash Dividend

(e)

The distribution of 2014, 2015 and 2016 were resolved at the shareholders’ meetings on June 3, 2015 and May 31, 2016 and May 26, 2017, respectively. Details are summarized below:


	2014				2015				2016
	Amount		Distribution per share		Amount		Distribution per share		Amount		Distribution per share
	NT$000		NT$		NT$000		NT$		NT$000		NT$
Legal reserve		331,863		—		223,047		—		28,680		—
Cash dividend		1,999,225		2.22		1,792,553		2.09		257,026		0.30
Cash distribution from capital surplus		—		—		—		—		599,728		0.70

Treasury stock (Tables)

12 Months Ended

Dec. 31, 2017

Movement of Treasury Stock

The movement of treasury stock is set out below:


	2015						2016				2017
	Shares (in thousands)			Amount (NT$000)			Shares (in thousands)		Amount (NT$000)		Shares (in thousands)		Amount (NT$000)		Amount (US$000)
January 1		—			—			—		—		30,085		1,007,654		33,997
Treasury stock (repurchased)		20,000			633,737			30,085		1,007,654		—		—		—
Treasury stock (cancelled)		(20,000	)		(633,737	)		—		—		—		—		—

December 31		—			—			30,085		1,007,654		30,085		1,007,654		33,997

Bank loans (Tables)

12 Months Ended

Dec. 31, 2017

Long-term bank loans [Member]

Summary of Bank Loans


Type of loans	Period and payment term	December 31, 2016			December 31, 2017			December 31, 2017
		NT$000			NT$000			US$000
Syndicated bank loan	Borrowing period is from June 30, 2016 to June 30, 2021; interest is repayable monthly; principal is repayable semi-annually from December 30, 2017.		10,800,000			9,675,301			326,427
Less: Fee on syndicated bank loan			(49,995	)		(33,280	)		(1,122	)
Less: Current portion (fee included)			(1,062,285	)		(2,143,168	)		(72,307	)

			9,687,720			7,498,853			252,998

Interest rate range			1.7895	%		1.7895	%		1.7895	%

Unused credit lines of long-term bank loans NT$000			2,400,000			2,400,000

Details of Repayment Schedule in Respect of Bank Loans

Details of the repayment schedule in respect of the bank loans are as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Less than 1 year

1,062,285

2,143,168

72,307

2 to 5 years

9,687,720

7,498,853

252,998

10,750,005

9,642,021

325,305

Short-term bank loans [member]

Summary of Bank Loans

December 31,
2016

December 31,
2017

NT$000

US$000

Unsecured bank loans

—

969,353

32,704

Annual interest rate

—

0.55%~1.71%

Unused Credit Lines of Bank Loans

Unused credit lines of short-term bank loans are as follows:


	December 31, 2016		December 31, 2017
NT$000		3,119,000		3,028,357
US$000		80,000		80,000

Retirement benefit plans (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Amounts Recognized in Statements of Financial Position

(b)

The amounts recognized in the statements of financial position are as follows:


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Present value of defined benefit obligations		(894,163	)		(838,543	)		(28,291	)
Fair value of plan assets		347,195			360,017			12,146

Net defined benefit liability		(546,968	)		(478,526	)		(16,145	)

Summary of Movements in net Defined Benefit Liability

(c)

Movements in net defined benefit liability are as follows:


	2016
	Present value of defined benefit obligations			Fair value of plan assets			Net defined benefit liability
	NT$000			NT$000			NT$000
January 1		(844,166	)		324,695			(519,471	)
Current service cost		(321	)		—			(321	)
Interest (expense) income		(14,644	)		5,768			(8,876	)

		(859,131	)		330,463			(528,668	)

Remeasurements:
Return of plan assets (not including the amount included in interest income or expense)		—			(3,413	)		(3,413	)
Financial assumption movement effect		(31,294	)		—			(31,294	)
Experience adjustments		(8,676	)		—			(8,676	)

		(39,970	)		(3,413	)		(43,383	)

Pension fund contribution		—			25,083			25,083
Paid pension		4,938			(4,938	)		—

December 31		(894,163	)		347,195			(546,968	)


	2017
	Present value of defined benefit obligations			Fair value of plan assets			Net defined benefit liability			Net defined benefit liability
	NT$000			NT$000			NT$000			US$000
January 1		(894,163	)		347,195			(546,968	)		(18,454	)
Current service cost		(386	)		—			(386	)		(13	)
Interest (expense) income		(13,236	)		5,226			(8,010	)		(270	)

		(907,785	)		352,421			(555,364	)		(18,737	)

Remeasurements:
Return of plan assets (not including the amount included in interest income or expense)		—			(1,842	)		(1,842	)		(62	)
Financial assumption movement effect		28,506			—			28,506			962
Experience adjustments		24,174			—			24,174			815

		52,680			(1,842	)		50,838			1,715

Pension fund contribution		—			26,000			26,000			877
Paid pension		16,562			(16,562	)		—			—

December 31		(838,543	)		360,017			(478,526	)		(16,145	)

Principal Actuarial Assumptions

(e)

The principal actuarial assumptions used were as follows:


	2016			2017
Discount rate used in determining present values		1.50	%		1.75	%
Expected future salary increases		3.50	%		3.50	%

Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions

The sensitivity analysis of present value of defined benefit obligations effected by the changes of significant actuarial assumptions at December 31, 2016 and 2017 are shown below:


	Discount rate					Future salary increases
	Increase 0.25%			Decrease 0.25%		Increase 0.25%		Decrease 0.25%
December 31, 2016
Effect on present value of defined benefit obligations		(31,294	)		32,893		32,174		(30,787	)

December 31, 2017
Effect on present value of defined benefit obligations		(27,192	)		28,506		27,955		(26,816	)

Analysis of Timing of the Future Pension Payment

(g)

As of December 31, 2017, the weighted average duration of that retirement plan is 13.4 years. The analysis of timing of the future pension payment is as follows:


	December 31, 2017
	NT$000		US$000
Within 1 year		28,007		945
1-2 years		31,702		1,070
2-5 years		102,703		3,465
6-10 years		178,720		6,029

		341,132		11,509

Other Payables (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Other Payables


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
Salaries and bonus payable		443,993		601,239		20,285
Interest payable		1,059		2,854		96
Accrued pension costs		29,930		32,402		1,093
Employees’ bonus		70,553		371,912		12,548
Directors’ remuneration		3,528		18,596		627
Other expense payable		862,991		953,179		32,159

		1,412,054		1,980,182		66,808

Provisions - current (Tables)

12 Months Ended

Dec. 31, 2017

Movements in Provisions

Movements

in provisions are as follows:


	2017
	Provisions for sales allowance			Provisions for deficiency compensation			Total			Total
	NT$000			NT$000			NT$000			US$000
January 1		66,065			14,654			80,719			2,723
Provision		117,234			119,318			236,552			7,981
Payment		(113,143	)		(76,817	)		(189,960	)		(6,409	)

December 31		70,156			57,155			127,311			4,295

Significant commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Future Minimum Lease Payments under Operating Lease Contracts

Future minimum lease payments under those leases are as follows:


	December 31, 2016		December 31, 2017		December 31, 2017
	NT$000		NT$000		US$000
£ 1 year		39,929		39,342		1,327
2 to 5 years		140,328		130,182		4,392
> 5 years		176,897		139,899		4,720

		357,154		309,423		10,439

Capital Expenditures that are Contracted for, but not Provided for

Capital expenditures that are contracted for, but not provided for are as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Property, plant and equipment

1,615,460

2,178,262

73,491

Transactions with non-controlling interests (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Effect on Equity Attributed to the Company from Transactions with Non-controlling Interests

The effect on the equity attributed to the Company during the period is summarized as follows:


	2015
	NT$000
Carrying amount of non-controlling interests acquired		2,637,316
Consideration paid to non-controlling interests		(2,921,041	)
Other component of equity		(17,964	)
Capital surplus		26,189

Retained earnings		(275,500	)

Supplementary cash flow information (Tables)

12 Months Ended

Dec. 31, 2017

Partial Cash Paid for Investing and Financing Activities

Partial cash paid for investing and financing activities

Property, plant and equipment


	2015			2016			2017			2017
	NT$000			NT$000			NT$000			US$000
Purchase in property, plant and equipment		3,644,560			4,690,995			4,849,331			163,608
Add: Beginning balance of payable to contractors and equipment suppliers		1,307,459			523,962			839,983			28,339
Add: Beginning balance of lease payable		—			—			94,952			3,204
Less: Ending balance of payable to contractors and equipment suppliers		(523,962	)		(647,486	)		(878,065	)		(29,624	)
Less: Ending balance of lease payable		—			(96,006	)		(84,192	)		(2,841	)
Less: Transfer from prepaid equipment (shown as “Other non-current assets”)		—			—			(139,304	)		(4,700	)

Cash paid for acquisition of property, plant and equipment		4,428,057			4,471,465			4,682,705			157,986

Treasury stock


	2015			2016		2017		2017
	NT$000			NT$000		NT$000		US$000
Repurchase of shares		1,862,362			1,007,654		—		—
Less: Beginning balance of prepayment for the repurchase of shares		(421,003	)		—		—		—

Cash paid for purchase of treasury stock		1,441,359			1,007,654		—		—

Capital reorganization


	2015		2016			2017		2017
	NT$000		NT$000			NT$000		US$000
Net assets acquired from ChipMOS Bermuda		—		12,987,736			—		—
Less: Issuance of shares		—		(9,779,426	)		—		—

Cash consideration		—		3,208,310			—		—
Directly attributable transaction cost		—		133,311			—		—

Cash paid for capital reorganization		—		3,341,621			—		—

Disposal of a subsidiary


	2015		2016		2017			2017
	NT$000		NT$000		NT$000			US$000
Disposal of a subsidiary		—		—		2,166,151			73,082
Add: Ending balance of other payables*		—		—		64,393			2,173
Less: Cash and cash equivalents of discontinued operations		—		—		(449,331	)		(15,160	)

Cash received from disposal of a subsidiary		—		—		1,781,213			60,095

Reconciliation of Liabilities Arising from Financing Activities

Reconciliation of liabilities arising from financing activities


						Non-Cash flow
	As of January 1, 2017		Cash flow*			Amortization of loans fee		As of December 31, 2017
	NT$000		NT$000			NT$000		NT$000		US$000
Long-term loans (include the current portion)		10,750,005		(1,124,699	)		16,715		9,642,021		325,305
Short-term loans		—		969,353			—		969,353		32,704
Guarantee deposits		1,404		(33	)		—		1,371		46

		10,751,409		(155,379	)		16,715		10,612,745		358,055

Related party transactions (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Significant Related Party Transactions

Significant related party transactions

(a)

Subcontracting fee


	2017		2017
	NT$000		US$000
ChipMOS Shanghai		41,183		1,389

(b)

Disposal of property, plant and equipment

2017

Selling price

Gain on disposal

NT$000

US$000

NT$000

US$000

ChipMOS Shanghai

21,982

742

20,240

683

Key Management Personnel Compensation

Key management personnel compensation


	2015		2016		2017		2017
	NT$000		NT$000		NT$000		US$000
Short-term employee benefits		217,091		152,319		188,105		6,346
Post-employment compensation		2,249		3,335		5,622		190
Share-based payments		100,280		109,255		18,736		632

		319,620		264,909		212,463		7,168

Pledged or mortgaged assets (Tables)

12 Months Ended

Dec. 31, 2017

Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases

The Group provided certain assets as collateral mainly for long-term bank loans (Note 22) and leases, which were as follows:

December 31,
2016

December 31,
2017

NT$000

US$000

Property, plant and equipment, net (Note 14)

8,020,905

7,164,089

241,703

Other financial assets – non current

70,677

70,241

2,370

8,091,582

7,234,330

244,073

Financial instruments by category (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Financial Instruments by Category

December 31,
2016

December 31,
2017

NT$000

US$000

Financial assets

Available-for-sale financial assets

9,960

20,890

705

Loans and receivables (including cash and cash equivalents, other financial assets, accounts and notes receivable, other receivables and refundable deposits)

11,862,621

12,204,292

411,751

11,872,581

12,225,182

412,456

Financial liabilities

Financial liabilities at amortized cost (including bank loans, accounts payable, payables to contractors and equipment suppliers, lease payable, other payables and guarantee deposits)

13,579,473

14,024,304

473,155

Financial risk management and fair values of financial instruments (Tables)

12 Months Ended

Dec. 31, 2017

Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations

The information on the assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows:


	December 31, 2016
	Foreign currency		Exchange rate		Carrying amount (NT$000)
Financial assets
Monetary items
US$000		178,201		32.2500		5,746,982
JPY000		517,114		0.2756		142,517
Financial liabilities
Monetary items
US$000		7,802		32.2500		251,615
JPY000		550,456		0.2756		151,706


	December 31, 2017
	Foreign currency		Exchange rate		Carrying amount (NT$000)
Financial assets
Monetary items
US$000		208,066		29.7600		6,192,044
JPY000		798,254		0.2642		210,899
RMB000		167,484		4.5650		764,564
Financial liabilities
Monetary items
US$000		16,036		29.7600		477,231
JPY000		1,071,432		0.2642		283,072

Details of Exposure to Currency Risk Arising from Recognized Monetary Assets or Liabilities Denominated in a Currency Other Than Functional Currency


	December 31, 2016
	Change in exchange rate			Effect on profit (NT$000)		Effect on other comprehensive income (NT$000)
Financial assets
US$000		5	%		287,349		—
JPY000		5	%		7,126		—
Financial liabilities
US$000		5	%		12,581		—
JPY000		5	%		7,585		—


	December 31, 2017
	Change in exchange rate			Effect on profit (NT$000)		Effect on other comprehensive income (NT$000)
Financial assets
US$000		5	%		309,602		—
JPY000		5	%		10,545		—
RMB000		5	%		38,228		—
Financial liabilities
US$000		5	%		23,862		—
JPY000		5	%		14,154		—

Maturity Profile of Non-derivative Financial Liabilities Based on Contracted Undiscounted Payments

The maturity profile of the Group’s non-derivative financial liabilities as of December 31, 2016 and 2017 based on the contracted undiscounted payments is as follows:


	December 31, 2016
	£ 1 year		2 to 5 years		> 5 years		Total
	NT$000		NT$000		NT$000		NT$000
Long-term bank loans (including current portion)		1,272,266		10,110,289		—		11,382,555
Accounts payable and payables to contractors and equipment suppliers		1,375,408		—		—		1,375,408
Other payables		1,412,054		—		—		1,412,054
Lease payable		12,000		30,000		—		42,000
Guarantee deposits		—		—		1,404		1,404

		4,071,728		10,140,289		1,404		14,213,421


	December 31, 2017
	£ 1 year		2 to 5 years		> 5 years		Total		Total
	NT$000		NT$000		NT$000		NT$000		US$000
Short-term bank loans		971,813		—		—		971,813		32,787
Long-term bank loans (including current portion)		2,321,459		7,740,267		—		10,061,726		339,465
Accounts payable and payables to contractors and equipment suppliers (including related parties)		1,401,499		—		—		1,401,499		47,284
Other payables (including related parties)		1,980,218		—		—		1,980,218		66,809
Lease payable		12,266		18,266		—		30,532		1,030
Guarantee deposits		—		—		1,371		1,371		46

		6,687,255		7,758,533		1,371		14,447,159		487,421

Share-based payments (Tables)

12 Months Ended

Dec. 31, 2017

Number and Weighted Average Exercise Prices of, and Movements in, Share Options

The following table illustrates the number and weighted average exercise prices (“WAEP”) of, and movements in, share options during the periods indicated:


	Ten months ended October 30, 2016			2016
	Number of options			WAEP US$
Outstanding at the beginning of the period		1,062,250			13.57
Forfeited		(25,084	)		15.35
Exercised		(97,715	)		7.21
Expired		(49,500	)		20.57
Early settled		(889,951	)		13.83

Outstanding at the end of the period		—			—

Exercisable at the end of the period		—			—

Number and Weighted Average Exercise Prices of, and Movements in, Share Appreciation Rights

The following table illustrates the number and WAEP of, and movements in, SARs during the periods indicated:


	Ten months ended October 30, 2016			2016
	Number of rights			WAEP US$
Outstanding at the beginning of the period		588,596			14.07
Granted		37,500			19.55
Forfeited		(9,785	)		15.16
Exercised		(123,033	)		11.26
Early settled		(493,278	)		15.17

Outstanding at the end of the period		—			—

Exercisable at the end of the period		—			—

Years of Service and Performance Conditions of Restricted Shares

When the employees of ChipMOS Taiwan accomplished the following years of service and performance conditions, the received restricted shares will be vested based on the vesting ratio.


	The 1^st year	The 2^nd year	The 3^rd year
Years of service following the receipt of restricted shares	Continuous service for one year	Continuous service for two years	Continuous service for three years
Grade of performance appraisal	>=B+	>=B+	>=B+
Compliance of terms agreed by the staff and the Company	No violation	No violation	No violation
Vesting ratio of numbers of restricted shares received	30%	30%	40%

Capital management (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Group Monitors Capital using Liabilities to Assets Ratio

The Group monitors capital using the liabilities to assets ratio, the percentages of which as of December 31, 2016 and 2017 were as follows:


	December 31, 2016			December 31, 2017			December 31, 2017
	NT$000			NT$000			US$000
Total liabilities		15,048,258			15,138,993			510,762

Total assets		31,295,960			33,259,942			1,122,130

Liabilities to assets ratio		48.08	%		45.52	%		45.52	%

Financial Statements Schedule: Valuation and Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure Of Details Of Valuation And Qualifying Accounts


	January 1		Additions charged to expense		Deduction / Write-offs			Exchange difference on translations of foreign financial statement			Non-current assets held for sale			December 31
	NT$000		NT$000		NT$000			NT$000			NT$000			NT$000
Year of 2015 :

Allowance for impairment of property, plant and equipment		2,110,362		1,478		(85,351	)		(31,774	)		—			1,994,715

Allowance for impairment of obsolescence and decline in market value of inventories		82,582		12,717		(151	)		(112	)		—			95,036

Year of 2016 :

Allowance for impairment of property, plant and equipment		1,994,715		8,198		(45,319	)		(118,046	)		(1,480,278	)		359,270

Allowance for impairment of obsolescence and decline in market value of inventories		95,036		66,894		—			(557	)		(6,532	)		154,841

Year of 2017 :

Allowance for impairment of property, plant and equipment		359,270		956		(39,771	)		—			—			320,455

Allowance for impairment of obsolescence and decline in market value of inventories		154,841		—		(101,127	)		—			—			53,714

Corporate and Group Information - Additional Information (Detail)				1 Months Ended
	Mar. 31, 2017	Oct. 30, 2016	Jun. 16, 2016	Mar. 31, 2017
Disclosure of corporate and group information [Line Items]
Percentage of equity interest held by former parent company, ChipMOS TECHNOLOGIES (Bermuda) LTD.		60.25%
ThaiLin Semiconductor Corp. [member]
Disclosure of corporate and group information [Line Items]
Percentage of equity interest in subsidiary			47.54%
ChipMOS TECHNOLOGIES (Shanghai) LTD. [member]
Disclosure of corporate and group information [Line Items]
Percentage of equity interest in subsidiary	45.02%
Percentage of equity interest in subsidiary to be sold	54.98%			54.98%

Basis of Presentation of Financial Statements and Principal Accounting Policies - Additional Information (Detail)		12 Months Ended
	Nov. 01, 2016	Dec. 31, 2017 TWD ($)	Jan. 01, 2018 TWD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Retained earnings		$ 2,815,966,000			$ 95,006,000	$ 260,989,000
Other receivables - related parties		4,534,000			153,000
Inventory		1,929,239,000			65,089,000	1,877,982,000
Deferred tax assets		212,372,000			7,165,000	249,806,000
Deferred tax liabilities		174,293,000			$ 5,880,000	$ 92,543,000
Financial assets measured at fair value		$ 0
Cash and cash equivalents maturity period		3 months
Effects of adopting new standards [member] \| Revenue recognition of customized products [member] \| Increase (decrease) due to application of IFRS 15 [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Retained earnings			$ 46,607,000	$ 1,572,000
Contract assets			255,112,000	8,607,000
Inventory			(208,505,000)	(7,035,000)
Effects of adopting new standards [member] \| Presentation of contract assets and contract liabilities [member] \| Increase (decrease) due to application of IFRS 15 [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Contract liabilities			70,156,000	2,367,000
Effects of adopting new standards [member] \| Recognition of deferred tax [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Deferred tax assets			(736,000)	(25,000)
Deferred tax liabilities			19,651,000	663,000
Effects of adopting new standards [member] \| IFRS 9 [member] \| Provision for impairment [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Retained earnings			(1,941,000)	(65,000)
Contract assets			(115,000)	(4,000)
Accounts receivable			(1,819,000)	(61,000)
Other receivables			(5,000)	(169)
Other receivables - related parties			(2,000)	(67)
Effects of adopting new standards [member] \| IFRS 9 [member] \| Financial assets at fair value through other comprehensive income, category [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Reclassification of available-for-sale financial assets			9,950,000	336,000
Financial assets at fair value through other comprehensive income			89,335,000	3,014,000
Retained earnings			28,584,000	964,000
Financial assets at fair value through other reserve			50,801,000	1,714,000
Effects of adopting new standards [member] \| IFRS 9 [member] \| Financial assets at fair value through profit or loss, category [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Reclassification of available-for-sale financial assets			10,940,000	369,000
Retained earnings			493,000	17,000
Financial assets at fair value through profit or loss			$ 11,433,000	$ 386,000
Certain properties [member] \| Other Property [Member] \| Top of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	11 years
Certain properties [member] \| Changes in accounting estimates of useful life of property, plant and equipment [member] \| Top of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	16 years
Certain equipment [member] \| Changes in accounting estimates of useful life of property, plant and equipment [member] \| Bottom of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	2 years
Certain equipment [member] \| Changes in accounting estimates of useful life of property, plant and equipment [member] \| Top of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	8 years
Certain equipment [member] \| office equipment [member] \| Bottom of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	2 years
Certain equipment [member] \| office equipment [member] \| Top of range [member]
Disclosure of detailed information about basis of presentation of financial statements and principal accounting policies [line items]
Estimated useful life of individual assets	6 years

Basis of Preparation of Financial Statements and Principal Accounting Policies - Summary of Ownership Interests in Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
ChipMOS USA Inc[member]
Disclosure of joint ventures [line items]
Name of investor	The Company
Main businesses	Research, development and marketing of semiconductors, circuits, and electronic related products
Location	San Jose, USA
Percentage of Ownership (%)	100.00%	100.00%
ChipMOS BVI [member]
Disclosure of joint ventures [line items]
Name of investor	The Company
Main businesses	Holding company
Location	British Virgin Islands
Percentage of Ownership (%)	100.00%	100.00%
ChipMOS Shanghai [member]
Disclosure of joint ventures [line items]
Name of investor	ChipMOS BVI
Main businesses	Semiconductor assembling and testing services
Location	People's Republic of China ("PRC")
Percentage of Ownership (%)		100.00%

Basis of Preparation of Financial Statements and Principal Accounting Policies - Impact on Depreciation Expenses of Current and Future Periods due to Change in Estimated Useful Lives of Certain Properties and Equipment (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Decrease in depreciation expenses	$ (119,737)
Within 1 year [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Decrease in depreciation expenses	(605,259)
1-2 years [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Decrease in depreciation expenses	(389,972)
2019 [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Decrease in depreciation expenses	$ (164,824)

Basis of Preparation of Financial Statements and Principal Accounting Policies - Estimated Useful Life for Depreciation of Individual Assets (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	6 years
Buildings [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	51 years
Machinery and equipment [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	2 years
Machinery and equipment [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	8 years
Tools [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	2 years
Tools [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	3 years
Other equipment [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	2 years
Other equipment [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	6 years

Segment Information - Financial Segment Information for Operating Segments (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Revenue
Revenue	$ 17,940,855	$ 605,292	$ 18,387,593	$ 18,837,089
Operating profit	2,239,881	75,570	1,998,575	2,648,427
Depreciation and amortization	(2,899,278)	(97,816)	(3,089,904)	(2,903,221)
Interest income	53,123	1,792	38,554	58,862
Interest expense	(190,425)	(6,425)	(144,545)	(126,621)
Share of profit (loss) of associates	(179,491)	(6,056)	28,924	31,269
Purchase of property, plant and equipment	4,702,691	158,660
Continuing operations [member]
Revenue
Revenue	17,940,855	605,292	18,387,593	18,837,089
Operating profit	2,239,881	75,570	1,998,575	2,648,427
Depreciation and amortization	(2,899,278)	(97,816)	(3,089,904)	(2,903,221)
Interest income	53,123	1,792	38,554	58,862
Interest expense	(190,425)	(6,425)	(144,545)	(126,621)
Share of profit (loss) of associates	(179,491)	(6,056)	28,924	31,269
Purchase of property, plant and equipment	4,702,691	158,660	3,123,312	3,644,560
Continuing operations [member] \| External [member]
Revenue
Revenue	17,940,855	605,292	18,387,593	18,837,089
Continuing operations [member] \| Operating segments [member] \| Testing [member]
Revenue
Revenue	4,838,246		4,587,054	4,718,658
Operating profit	1,448,939		1,346,874	1,203,169
Depreciation and amortization	(673,393)		(664,026)	(646,545)
Purchase of property, plant and equipment	836,894		771,500	796,964
Continuing operations [member] \| Operating segments [member] \| Testing [member] \| External [member]
Revenue
Revenue	4,838,246		4,587,054	4,546,394
Continuing operations [member] \| Operating segments [member] \| Testing [member] \| Intersegment [member]
Revenue
Revenue				172,264
Continuing operations [member] \| Operating segments [member] \| Assembly [member]
Revenue
Revenue	5,259,281		5,881,883	5,526,110
Operating profit	(55,198)		143,220	117,127
Depreciation and amortization	(597,500)		(635,481)	(550,819)
Purchase of property, plant and equipment	655,879		554,162	895,767
Continuing operations [member] \| Operating segments [member] \| Assembly [member] \| External [member]
Revenue
Revenue	5,259,281		5,880,780	5,525,582
Continuing operations [member] \| Operating segments [member] \| Assembly [member] \| Intersegment [member]
Revenue
Revenue			1,103	528
Continuing operations [member] \| Operating segments [member] \| LCDD [member]
Revenue
Revenue	4,790,116		4,920,302	5,396,001
Operating profit	1,285,495		963,698	1,354,398
Depreciation and amortization	(1,048,587)		(1,167,908)	(1,157,809)
Purchase of property, plant and equipment	2,615,153		910,457	1,366,389
Continuing operations [member] \| Operating segments [member] \| LCDD [member] \| External [member]
Revenue
Revenue	4,789,869		4,920,302	5,396,001
Continuing operations [member] \| Operating segments [member] \| LCDD [member] \| Intersegment [member]
Revenue
Revenue	247
Continuing operations [member] \| Operating segments [member] \| Bumping [member]
Revenue
Revenue	3,053,459		2,999,967	3,369,112
Operating profit	(336,123)		(341,356)	28,605
Depreciation and amortization	(579,605)		(622,412)	(548,234)
Purchase of property, plant and equipment	594,765		887,144	589,615
Continuing operations [member] \| Operating segments [member] \| Bumping [member] \| External [member]
Revenue
Revenue	3,053,459		2,999,457	3,369,112
Continuing operations [member] \| Operating segments [member] \| Bumping [member] \| Intersegment [member]
Revenue
Revenue			510
Continuing operations [member] \| Operating segments [member] \| Others [member]
Revenue
Revenue	35,808		41,670	44,577
Operating profit	(100,545)		(82,331)	(47,191)
Depreciation and amortization	(503)		(565)	(357)
Interest income	53,123		51,756	60,552
Interest expense	(190,425)		(144,545)	(128,311)
Share of profit (loss) of associates	1,347,851		(128,866)	25,346
Purchase of property, plant and equipment			49	2,477
Continuing operations [member] \| Operating segments [member] \| Others [member] \| Intersegment [member]
Revenue
Revenue	35,808		41,670	44,577
Continuing operations [member] \| Elimination [member]
Revenue
Revenue	(36,055)		(43,283)	(217,369)
Operating profit	(2,687)		(31,530)	(7,681)
Depreciation and amortization	310		488	543
Interest income			(13,202)	(1,690)
Interest expense				1,690
Share of profit (loss) of associates	(1,527,342)		157,790	5,923
Purchase of property, plant and equipment				(6,652)
Continuing operations [member] \| Elimination [member] \| Intersegment [member]
Revenue
Revenue	(36,055)		(43,283)	(217,369)
Discontinued operations: ChipMOS Shanghai [member]
Revenue
Revenue	227,095	7,662	1,005,166	1,032,302
Operating profit	(25,394)	(857)	(146,263)	(61,214)
Depreciation and amortization			(141,375)	(118,702)
Interest income	464	16	3,753	9,421
Interest expense	(2,414)	(81)	(606)	(414)
Purchase of property, plant and equipment			1,567,683
Discontinued operations: ChipMOS Shanghai [member] \| External [member]
Revenue
Revenue	$ 227,095	$ 7,662	$ 1,005,166	$ 1,032,302

Segment Information - Geographic Information of Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of geographical areas [Line Items]
Revenue	$ 17,940,855	$ 605,292	$ 18,387,593	$ 18,837,089
ROC [member]
Disclosure of geographical areas [Line Items]
Revenue	13,152,419	443,739	12,728,014	13,529,739
Japan [member]
Disclosure of geographical areas [Line Items]
Revenue	2,257,296	76,157	1,855,674	986,403
Singapore [member]
Disclosure of geographical areas [Line Items]
Revenue	1,798,585	60,681	3,087,835	2,928,591
Others [member]
Disclosure of geographical areas [Line Items]
Revenue	$ 732,555	$ 24,715	$ 716,070	$ 1,392,356

The income arising in the course of an entity's ordinary activities. Income is increases in economic benefits during the accounting period in the form of inflows or enhancements of assets or decreases of liabilities that result in an increase in equity, other than those relating to contributions from equity participants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 28
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_28_a&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 23
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_23_a&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 32
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_32&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 33
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_33_a&doctype=Standard
-URIDate 2017-03-09

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2017-01-01
-Paragraph 34
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_34&doctype=Standard
-URIDate 2017-03-09

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 82
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_82_a&doctype=Standard
-URIDate 2017-03-09

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 103
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_103&doctype=Standard
-URIDate 2017-03-09

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2018-01-01
-Name IAS
-Number 18
-IssueDate 2017-01-01
-Paragraph 35
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=18&date=2017-03-02&anchor=para_35_b&doctype=Standard&book=B
-URIDate 2017-03-09

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 102
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_102&doctype=Standard
-URIDate 2017-03-09

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2017-01-01
-Paragraph B12
-Subparagraph b
-Clause v
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B12_b_v&doctype=Appendix&seq=2
-URIDate 2017-03-09

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 12
-IssueDate 2017-01-01
-Paragraph B10
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B10_b&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Segment Information - Net Revenue from Customers Representing at Least 10% of Total Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of major customers [Line Items]
Net revenue	$ 17,940,855	$ 605,292	$ 18,387,593	$ 18,837,089
Customer A [member]
Disclosure of major customers [Line Items]
Net revenue	$ 3,434,873	$ 115,886	$ 3,370,285	$ 4,307,855
Percentage of total revenue	19.00%	19.00%	18.00%	23.00%
Customer K [member]
Disclosure of major customers [Line Items]
Net revenue	$ 2,742,882	$ 92,540	$ 2,633,431	$ 2,386,975
Percentage of total revenue	15.00%	15.00%	14.00%	13.00%
Customer I [member]
Disclosure of major customers [Line Items]
Net revenue	$ 1,798,111	$ 60,665	$ 3,085,190	$ 2,935,820
Percentage of total revenue	10.00%	10.00%	17.00%	16.00%
Customer C [member]
Disclosure of major customers [Line Items]
Net revenue	$ 1,530,209	$ 51,626	$ 1,870,675	$ 1,761,049
Percentage of total revenue	9.00%	9.00%	10.00%	9.00%

+ References

+ Details

Operating Costs and Expenses - Summary of Operating Costs and Expenses (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Analysis of income and expense [abstract]
Change of finished goods and work in process	$ 31,977	$ 1,079	$ (19,498)	$ 7,899
Consumption of raw materials and supplies	3,036,350	102,441	3,346,540	3,271,581
Employee benefit expenses	5,895,778	198,913	5,317,125	5,358,962
Depreciation and amortization	2,899,278	97,816	3,089,904	2,903,221
Other expenses	4,530,425	152,848	4,745,253	4,752,050
Total operating costs and expenses	16,393,808	553,097	16,479,324	16,293,713
Employee benefit expenses
Salaries	4,874,709	164,464	4,126,203	4,300,550
Labor and health insurance	390,788	13,184	351,232	355,331
Pension	198,502	6,697	183,293	179,665
Share-based payments	123,021	4,151	356,463	207,242
Other personnel expenses	308,758	10,417	299,934	316,174
Total employee benefit costs	$ 5,895,778	$ 198,913	$ 5,317,125	$ 5,358,962

Other Operating Income (Expenses), Net - Summary of Other Operating Income (Expenses), Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of other operating income expense [Line Items]
Gain on disposal of property, plant and equipment, net	$ 132,777	$ 4,480	$ 2,575	$ 1,562
Impairment on property, plant and equipment	(956)	(32)
Gain on disposal of scrapped materials	27,940	943	30,476	31,870
Gain on disposal of items purchased on behalf of others	26,417	891	48,812	22,893
Royalty income	11,998	405
Insurance compensation income	486,858	16,426	7,033
Others	7,800	262	9,608	50,186
Other operating income (expenses), net	692,834	23,375	90,306	105,051
Continuing operations [member]
Disclosure of other operating income expense [Line Items]
Impairment on property, plant and equipment	$ (956)	$ (32)	$ (8,198)	$ (1,460)

Finance Costs - Summary of Finance Costs (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Analysis of income and expense [abstract]
Interest on bank loans	$ 208,486	$ 7,034	$ 157,254	$ 146,003
Interest on lease payable	708	24	212
Less: Amounts capitalized in qualifying assets	(18,769)	(633)	(12,921)	(19,382)
Interest expense	190,425	6,425	144,545	126,621
Finance expense	26,858	906	34,571	15,890
Finance cost net	$ 217,283	$ 7,331	$ 179,116	$ 142,511

Other Non-operating Income (Expenses), Net - Summary of Other Non-operating Income (Expenses), Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Analysis of income and expense [abstract]
Interest income	$ 53,123	$ 1,792	$ 38,554	$ 58,862
Foreign exchange gains (losses), net	(418,970)	(14,135)	(195,326)	241,983
Impairment of available-for-sale financial assets				(8,584)
Gain on disposal of financial assets at fair value through profit or loss	637	22	621	11,483
Gain on disposal of long-term investment in associates	16,929	571
Share of profit (loss) of associates	(179,491)	(6,056)	28,924	31,269
Reimbursement of ADSs service charge	23,707	800
Others	13,883	468	8,203	5,127
Other non-operating income (expenses), net	$ (490,182)	$ (16,538)	$ (119,024)	$ 340,140

Income Tax Expense - Additional Information (Detail) $ in Thousands, $ in Thousands		12 Months Ended
	Oct. 31, 2016 TWD ($)	Dec. 31, 2017 TWD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015	Dec. 31, 2017 USD ($)
Disclosure of income tax expense [Line Items]
Statutory tax rates		17.00%	17.00%	17.00%
Reduction of unappropriated retained earnings through capital transfer	$ (5,052,343)		$ (5,052,343)
Tax on unappropriated retained earnings				10.00%
Deductible temporary differences		$ 28,584	534,568		$ 964
Taxable temporary differences		$ 920,943			$ 31,071
Balance of imputation tax credit account			$ 1,192,119
Imputation tax credit, Creditable tax rate			20.48%
ThaiLin Semiconductor Corp. [member]
Disclosure of income tax expense [Line Items]
Statutory tax rates				17.00%
ChipMOS TECHNOLOGIES (Shanghai) LTD. [member]
Disclosure of income tax expense [Line Items]
Statutory tax rates		25.00%	25.00%	25.00%

Income Tax Expense - Major Components of Income Tax Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Current income tax:
Current income tax on profits for the period	$ 125,376	$ 4,230	$ 331,144	$ 720,461
Income tax (benefit) on unappropriated retained earnings	246,684	8,322	(174,930)	198,157
Prior year income tax (over) under estimation	67,885	2,290	4,527	(1,732)
Total current income tax	439,945	14,842	160,741	916,886
Deferred income tax:
Relating to origination and reversal of temporary differences	110,542	3,730	16,379	18,969
Total deferred income tax	110,542	3,730	16,379	18,969
Income tax expense reported in the consolidated statements of comprehensive income	$ 550,487	$ 18,572	$ 177,120	$ 935,855

The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax that relate to continuing operations. [Refer: Continuing operations [member]; Current tax expense (income); Deferred tax expense (income)]

Income Tax Expense - Deferred Tax Charged to Other Comprehensive Income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Income tax relating to components of other comprehensive income [abstract]
Remeasurement of defined benefit obligations	$ 8,642	$ 292	$ (7,375)	$ (7,099)

Income Tax Expense - Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Reconciliation of accounting profit multiplied by applicable tax rates [abstract]
Tax calculated based on profit before tax and statutory tax rate	$ 566,649	$ 19,118	$ 214,550	$ 462,692
Expenses disallowed (added) by tax regulations	10,185	344	(2,190)	5,692
Temporary difference not recognized as deferred tax assets	(85,168)	(2,873)	1,306	6,522
Tax exempted (income) expenses by tax regulation	(256,788)	(8,664)	12,057	(13,483)
Taxable loss not recognized as deferred tax assets			54,012	25,737
Effect of different tax rates in countries in which the Group operates	1,040	35	10,451	3,100
Withholding tax			57,337	249,170
Prior year income tax (over) under estimation	67,885	2,290	4,527	(1,732)
Income tax (benefit) on unappropriated retained earnings	246,684	8,322	(174,930)	198,157
Income tax expense reported in the consolidated statements of comprehensive income	$ 550,487	$ 18,572	$ 177,120	$ 935,855

Income Tax Expense - Details of Deferred Tax Assets (Liabilities) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Profit and loss	$ (110,542)	$ (3,730)	$ (16,379)	$ (18,969)
Unrealized exchange losses deferred tax assets [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance			(5,843)
Profit and loss	8,167		5,843
Ending balance	8,167	276		(5,843)
Inventories [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	26,324		14,823
Profit and loss	(17,192)		11,501
Ending balance	9,132	308	26,324	14,823
Property, plant and equipment, deferred tax assets [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	80,869		3,672
Profit and loss	(25,375)		77,197
Ending balance	55,494	1,872	80,869	3,672
Deferred income [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	41,294		50,423
Profit and loss	(1,809)		(9,129)
Ending balance	39,485	1,332	41,294	50,423
Provisions [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	11,232		16,473
Profit and loss	10,411		(5,241)
Ending balance	21,643	730	11,232	16,473
Net defined benefit liability, non-current [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	90,087		86,719
Profit and loss	(2,994)		(4,007)
Other comprehensive income	(8,642)		7,375
Ending balance	78,451	2,647	90,087	86,719
Deferred tax asset [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	249,806		166,267
Profit and loss	(28,792)		76,164
Other comprehensive income	(8,642)		7,375
Ending balance	212,372	7,165	249,806	$ 166,267
Unrealised exchange gains (losses), deferred tax liabilities [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(14,155)
Profit and loss	14,155		(14,155)
Ending balance			(14,155)
Property, plant and equipment, deferred tax liabilities [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(78,388)
Profit and loss	(95,905)		(78,388)
Ending balance	(174,293)	(5,880)	(78,388)
Deferred tax liabilities [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(92,543)
Profit and loss	(81,750)		(92,543)
Ending balance	$ (174,293)	$ (5,880)	$ (92,543)

Earnings Per Share ("EPS") - Income and Share Data Used in Basic and Diluted EPS Computations (Detail) $ / shares in Units, $ / shares in Units, shares in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 TWD ($) $ / shares shares	Dec. 31, 2015 TWD ($) $ / shares shares
Basic earnings per share, amount after tax
Equity holders of the Company - Continuing operations, amount after tax	$ 981,929	$ 33,129	$ 1,829,327	$ 2,164,557
Equity holders of the Company - Discontinued operations, amount after tax	1,814,953	61,233	(122,105)	(34,233)
Equity holders of the Company, amount after tax \| $	2,796,882		1,707,222	2,130,324
Predecessors' interests, amount after tax			(306,012)	(291,429)
Profit (loss) attributable to equity holders of the Company, amount after tax \| $			1,401,210	1,838,895
Diluted earnings per share, amount after tax
Equity holders of the Company - Continuing operations, amount after tax	981,929	33,129	1,829,327	2,164,557
Equity holders of the Company - Discontinued operations, amount after tax	1,814,953	61,233	(122,105)	(34,233)
Equity holders of the Company, amount after tax \| $	2,796,882		1,707,222	2,130,324
Predecessors' interests, amount after tax			(306,012)	(291,429)
Profit (loss) attributable to equity holders of the Company, amount after tax \| $			$ 1,401,210	$ 1,838,895
Basic and diluted earnings per share, weighted-average number of ordinary shares outstanding
Weighted-average number of ordinary shares outstanding \| shares	846,686	846,686	859,644	877,402
Employees' bonuses \| shares	14,034	14,034	3,035	10,867
Restricted shares \| shares	5,075	5,075	4,122	27
Weighted-average number of ordinary shares outstanding \| shares	865,795	865,795	866,801	888,296
Ordinary shares [member]
Basic earnings per share
Equity holders of the Company - Continuing operations, earnings per share \| (per share)	$ 1.16	$ 0.04	$ 2.13	$ 2.47
Equity holders of the Company - Discontinued operations, earnings per share \| (per share)	2.14	0.07	(0.14)	(0.04)
Basic earnings per share \| (per share)	3.30	0.11	1.99	2.43
Predecessors' interests, earnings per share \| (per share)			(0.35)	(0.33)
Basic earnings per share \| (per share)	3.30	0.11	1.64	2.10
Diluted earnings per share
Equity holders of the Company - Continuing operations, earnings per share \| (per share)	1.13	0.04	2.11	2.44
Equity holders of the Company - Discontinued operations, earnings per share \| (per share)	2.10	0.07	(0.14)	(0.04)
Diluted earnings per share \| (per share)	3.23	0.11	1.97	2.40
Predecessors' interests, earnings per share \| (per share)			(0.35)	(0.33)
Diluted earnings per share \| (per share)	$ 3.23	$ 0.11	$ 1.62	$ 2.07

Dividend - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands	Jul. 12, 2017 TWD ($)	Jul. 12, 2017 USD ($)	May 26, 2017 $ / shares	Dec. 19, 2016 TWD ($)	May 31, 2016 $ / shares
Disclosure of dividends [Line Items]
Dividend paid			$ 1.00		$ 2.09
Dividend paid	$ 856,754	$ 28,906		$ 1,792,553
Capital surplus [member]
Disclosure of dividends [Line Items]
Dividend paid			$ 0.70

Available-for-Sale Financial Assets - Summary of Available-for-Sale Financial Assets (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	$ 20,890	$ 705	$ 9,960
Gross carrying amount [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	49,474	1,669	79,880
Allowance for impairment losses [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	$ (28,584)	$ (964)	$ (69,920)

Available-for-Sale Financial Assets - Additional Information (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
VIGOUR TECHNOLOGY Corporation [member]
Disclosure of financial assets [Line Items]
Impairment loss of investments	$ 41,336	$ 1,395

Investment in Associates - Details of Investment in Associates (Detail) $ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2017 TWD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2017 USD ($)
Disclosure of associates [line items]
Carrying amount		$ 3,433,332	$ 369,329	$ 115,834
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Country of incorporation and business		Kaohsiung Taiwan
Measurement method		Equity method
Carrying amount		$ 373,276	$ 369,329	12,593
Ownership	19.10%	19.10%	21.22%
ChipMOS Shanghai [member]
Disclosure of associates [line items]
Country of incorporation and business		Shanghai PRC
Measurement method		Equity method
Carrying amount		$ 3,060,056		$ 103,241
Ownership		45.02%

Investment in Associates - Additional Information (Detail) $ in Thousands, $ in Thousands	1 Months Ended			12 Months Ended
	Jun. 30, 2017 TWD ($)	Jun. 30, 2017 USD ($)	Jan. 31, 2017	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)	Mar. 31, 2017	Jun. 17, 2015
Disclosure of associates [line items]
Sale of equity percentage									52.46%
Acquisition of investment in associate				$ 1,373,486	$ 46,339		$ 116,000
Share of profit (loss) of investment associates				$ (179,491)	$ (6,056)	$ 28,924
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Percentage of ownership interest in associate			19.10%	19.10%	19.10%	21.22%
Disposal gain from long-term investment				$ 16,929	$ 571
ChipMOS Shanghai [member]
Disclosure of associates [line items]
Percentage of ownership interest in associate				45.02%	45.02%
Sale of equity percentage								54.98%
Acquisition of investment in associate	$ 1,373,486	$ 46,339

Investment in Associates - Summarized Financial Information for Investment in Material Associates (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)	Dec. 31, 2017 USD ($)
Disclosure of associates [line items]
Current assets	$ 14,200,980		$ 16,895,957		$ 479,115
Non-current assets	19,058,962		14,400,003		643,015
Current liabilities	(6,942,995)		(4,690,312)		(234,244)
Non-current liabilities	(8,195,998)		(10,357,946)		(276,518)
Carrying amount	3,433,332		369,329		115,834
Revenue	17,940,855	$ 605,292	18,387,593	$ 18,837,089
Profit (loss) for the year from continuing operations	981,929	33,129	1,523,315	1,910,201
Other comprehensive income, net of income tax	(189,902)	(6,407)	(236,421)	(47,200)
Total comprehensive income	2,606,980	87,955	1,164,789	$ 1,828,768
ChipMOS Shanghai [member]
Disclosure of associates [line items]
Current assets	3,380,641				114,056
Non-current assets	2,766,839				93,348
Current liabilities	(460,054)				(15,521)
Non-current liabilities	(489,097)				(16,501)
Total net assets	5,198,329				175,382
Group's share	2,340,506				78,965
Depreciable assets	703,536				23,736
Goodwill	22,118				746
Inter-company transactions and amortization	(6,104)				(206)
Carrying amount	3,060,056				103,241
Revenue	1,141,415	38,509
Profit (loss) for the year from continuing operations	(348,472)	(11,757)
Total comprehensive income	(348,472)	(11,757)
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Current assets	833,914		904,571		28,134
Non-current assets	1,161,620		876,314		39,191
Current liabilities	(284,580)		(258,513)		(9,601)
Non-current liabilities	(1,756)		(2,491)		(59)
Total net assets	1,709,198		1,519,881		57,665
Group's share	326,456		322,509		11,014
Goodwill	46,820		46,820		1,579
Carrying amount	373,276		369,329		$ 12,593
Revenue	1,322,928	44,633	1,667,761
Profit (loss) for the year from continuing operations	4,414	149	136,303
Other comprehensive income, net of income tax	2,903	98	(627)
Total comprehensive income	7,317	247	135,676
Dividend received from the associate	$ 14,325	$ 483	$ 5,730

Property, Plant and Equipment, Net - Summary of Property, Plant and Equipment, Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	$ 15,531,186	$ 523,994
Less: Property, plant and equipment classified as held for sale	(2,033,968)	(68,622)	$ (2,033,968)
Beginning Balance	13,497,218	455,372	14,211,560
Additions	4,702,691	158,660
Disposals	(34,233)	(1,155)
Depreciation expenses	(2,899,278)	(97,816)
Impairment losses	(956)	(32)
Exchange adjustments	(131)	(5)
Ending Balance			15,531,186
Ending Balance	15,265,311	515,024	13,497,218
Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738
Beginning Balance	452,738		452,738
Ending Balance			452,738
Ending Balance	452,738		452,738
Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	4,787,946
Less: Property, plant and equipment classified as held for sale	(710,191)		(710,191)
Beginning Balance	4,077,755		4,836,680
Additions	211,098
Reclassifications	141,400
Depreciation expenses	(511,167)
Ending Balance			4,787,946
Ending Balance	3,919,086		4,077,755
Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	7,571,620
Less: Property, plant and equipment classified as held for sale	(433,688)		(433,688)
Beginning Balance	7,137,932		7,342,705
Additions	2,007,767
Disposals	(30,066)
Reclassifications	1,535,619
Depreciation expenses	(1,837,482)
Exchange adjustments	(43)
Ending Balance			7,571,620
Ending Balance	8,813,727		7,137,932
Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	524,443
Less: Property, plant and equipment classified as held for sale	(90,460)		(90,460)
Beginning Balance	433,983		349,774
Additions	571,601
Disposals	(2,302)
Reclassifications	44,882
Depreciation expenses	(357,695)
Ending Balance			524,443
Ending Balance	690,469		433,983
Other equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	566,623
Less: Property, plant and equipment classified as held for sale	(168,314)		(168,314)
Beginning Balance	398,309		403,560
Additions	195,957
Disposals	(1,865)
Reclassifications	22,149
Depreciation expenses	(192,934)
Impairment losses	(956)
Exchange adjustments	(88)
Ending Balance			566,623
Ending Balance	420,572		398,309
Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	1,627,816
Less: Property, plant and equipment classified as held for sale	(631,315)		(631,315)
Beginning Balance	996,501		826,103
Additions	1,716,268
Reclassifications	(1,744,050)
Ending Balance			1,627,816
Ending Balance	968,719		996,501
Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	67,619,367	2,281,355
Beginning Balance			64,645,094
Ending Balance			67,619,367
Ending Balance	63,638,420	2,147,045
Gross carrying amount [member] \| Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738
Beginning Balance			452,738
Ending Balance			452,738
Ending Balance	452,738
Gross carrying amount [member] \| Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	11,183,278
Beginning Balance			10,700,236
Ending Balance			11,183,278
Ending Balance	9,809,970
Gross carrying amount [member] \| Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	47,002,228
Beginning Balance			45,945,380
Ending Balance			47,002,228
Ending Balance	45,778,207
Gross carrying amount [member] \| Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	3,999,894
Beginning Balance			3,673,636
Ending Balance			3,999,894
Ending Balance	4,004,703
Gross carrying amount [member] \| Other equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	3,353,413
Beginning Balance			3,047,001
Ending Balance			3,353,413
Ending Balance	2,624,083
Gross carrying amount [member] \| Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	1,627,816
Beginning Balance			826,103
Ending Balance			1,627,816
Ending Balance	968,719
Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(52,088,181)	(1,757,361)
Beginning Balance			(50,433,534)
Ending Balance			(52,088,181)
Ending Balance	(48,373,109)	$ (1,632,021)
Accumulated depreciation and impairment [member] \| Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(6,395,332)
Beginning Balance			(5,863,556)
Ending Balance			(6,395,332)
Ending Balance	(5,890,884)
Accumulated depreciation and impairment [member] \| Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(39,430,608)
Beginning Balance			(38,602,675)
Ending Balance			(39,430,608)
Ending Balance	(36,964,480)
Accumulated depreciation and impairment [member] \| Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(3,475,451)
Beginning Balance			(3,323,862)
Ending Balance			(3,475,451)
Ending Balance	(3,314,234)
Accumulated depreciation and impairment [member] \| Other equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(2,786,790)
Beginning Balance			(2,643,441)
Ending Balance			(2,786,790)
Ending Balance	$ (2,203,511)
Property, plant and equipment, net, including held for sale [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			4,690,995
Disposals			(9,026)
Depreciation expenses			(3,228,441)
Impairment losses			(8,198)
Exchange adjustments			(125,704)
Property, plant and equipment, net, including held for sale [member] \| Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			255,916
Disposals			(51)
Reclassifications			372,448
Depreciation expenses			(631,233)
Exchange adjustments			(45,814)
Property, plant and equipment, net, including held for sale [member] \| Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			934,913
Disposals			(8,624)
Reclassifications			1,509,798
Depreciation expenses			(2,188,976)
Exchange adjustments			(18,196)
Property, plant and equipment, net, including held for sale [member] \| Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			358,413
Reclassifications			22,882
Depreciation expenses			(201,755)
Exchange adjustments			(4,871)
Property, plant and equipment, net, including held for sale [member] \| Other equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			351,850
Disposals			(351)
Reclassifications			37,373
Depreciation expenses			(206,477)
Impairment losses			(8,198)
Exchange adjustments			(11,134)
Property, plant and equipment, net, including held for sale [member] \| Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Additions			2,789,903
Reclassifications			(1,942,501)
Exchange adjustments			$ (45,689)

Property, Plant and Equipment, Net - Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Capitalization interest	$ 18,769	$ 633
Capitalization interest rate applied	1.7624%	1.7624%
Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Capitalization interest rate applied			1.7456%
Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Capitalization interest			$ 13,435
Capitalization interest rate applied			3.6166%

Inventories - Summary of Inventories (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of inventories [Line Items]
Raw materials	$ 1,720,734	$ 58,054	$ 1,647,347
Work in process	176,089	5,941	176,620
Finished goods	32,416	1,094	54,015
Inventories	1,929,239	$ 65,089	1,877,982
Gross carrying amount [member]
Disclosure of inventories [Line Items]
Raw materials	1,769,917		1,787,810
Work in process	180,252		190,823
Finished goods	32,784		54,190
Inventories	1,982,953		2,032,823
Allowance for impairment losses [member]
Disclosure of inventories [Line Items]
Raw materials	(49,183)		(140,463)
Work in process	(4,163)		(14,203)
Finished goods	(368)		(175)
Inventories	$ (53,714)		$ (154,841)

Inventories - Cost of Inventories Recognized as an Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Analysis of income and expense [abstract]
Cost of revenue	$ 14,766,555	$ 498,197	$ 14,670,711
Loss on abandonment	38,301	1,292	7,098
Allowance for (reversal of) inventory valuation and obsolescence loss	(101,127)	(3,412)	67,663
Cost of revenue	$ 14,703,729	$ 496,077	$ 14,745,472	$ 14,685,514

Accounts and Notes and Other Receivables - Summary of Accounts and Notes and Other Receivables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of financial assets [Line Items]
Accounts and notes receivable	$ 4,015,734	$ 135,484	$ 4,140,246
Other receivables	56,716	1,914	57,411
Accounts and notes and other receivables	4,072,450	137,398	4,197,657
Gross carrying amount [member]
Disclosure of financial assets [Line Items]
Other receivables	56,716	1,914	57,411
Gross carrying amount [member] \| Accounts receivable [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	4,013,705	135,415	4,138,580
Gross carrying amount [member] \| Notes receivable [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	$ 2,029	$ 69	1,753
Allowance for impairment losses [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable			$ (87)

Accounts and Notes and Other Receivables - Movements in Allowance for Impairment of Accounts and Other Receivables (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Beginning balance	$ 87
Reversal of allowance for impairment losses	(87)
Impairment losses recognized			$ 87
Ending balance			87
Other receivables [member]
Disclosure of financial assets [Line Items]
Beginning balance	0		0
Impairment losses recognized			0
Ending balance	$ 0	$ 0	$ 0

Accounts and Notes and Other Receivables - Ageing of Accounts Receivable which are Past Due but not Impaired (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of financial assets [Line Items]
Accounts and notes receivable	$ 4,015,734	$ 135,484	$ 4,140,246
Accounts receivable [member] \| Financial assets past due but not impaired [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	15,872	535	27,310
Accounts receivable [member] \| Financial assets past due but not impaired [member] \| Less than or equal to 1 month [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	10,482	354	24,141
Accounts receivable [member] \| Financial assets past due but not impaired [member] \| 1 - 2 months [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	477	16	728
Accounts receivable [member] \| Financial assets past due but not impaired [member] \| 2 - 3 months [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	426	14	183
Accounts receivable [member] \| Financial assets past due but not impaired [member] \| 3 - 4 months [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	1,431	48	245
Accounts receivable [member] \| Financial assets past due but not impaired [member] \| More than 4 months [member]
Disclosure of financial assets [Line Items]
Accounts and notes receivable	$ 3,056	$ 103	$ 2,013

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 TWD ($)	Dec. 31, 2014 TWD ($)
Cash and cash equivalents [abstract]
Short-term deposits	$ 3,883,614	$ 131,026	$ 3,854,354
Cash	470	16	525
Cash at banks	4,151,630	140,068	4,106,384
Cash and cash equivalents, different from consolidated statements of financial position	8,035,714	271,110	7,961,263	$ 268,599	$ 12,127,350	$ 15,265,153
Less: Cash and cash equivalents classified as non-current assets held for sale			(389,897)
Cash and cash equivalents	$ 8,035,714	$ 271,110	$ 7,571,366

Cash and Cash Equivalents - Additional Information (Detail) - TWD ($)	Dec. 31, 2017	Dec. 31, 2016
Cash and cash equivalents [abstract]
Cash and cash equivalents classified and shown as "non-current assets held for sale"		$ 389,897,000
Cash and cash equivalents pledge	$ 0	$ 0

Non-current Assets Held for Sale and Discontinued Operations - Additional Information (Detail) $ in Thousands, $ in Thousands		1 Months Ended
	Mar. 31, 2017	Mar. 31, 2017 TWD ($)	Mar. 31, 2017 USD ($)
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Cash consideration		$ 2,230,544	$ 75,255
Gain loss on disposal of discontinued operations		$ 1,843,234	$ 62,187
Percentage of disposal of equity interest		54.98%	54.98%
Fair value of gain loss on disposal of equity interest		$ 999,630	$ 33,726
Percentage of fair value gain on remeasurement of retained investment		45.02%	45.02%
Fair value of gain on remeasurement of retained investment		$ 843,604	$ 28,461
ChipMOS TECHNOLOGIES (Shanghai) LTD. [member]
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Equity interest in subsidiary to be sold	54.98%	54.98%	54.98%

Non-current Assets Held for Sale and Discontinued Operations - Cash Flow Information of Discontinued Operations (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract]
Net cash generated from (used in) operating activities	$ (109,079)	$ (3,680)	$ (1,109,029)	$ 1,072,628
Net cash used in investing activities	(272,925)	(9,208)	(1,331,564)	(205,292)
Net cash generated from (used in) financing activities	461,312	15,564	1,463,664	(91,234)
Effect of foreign exchange rate changes	(19,874)	(671)	(61,336)	(18,636)
Net increase (decrease) in cash and cash equivalents	$ 59,434	$ 2,005	$ (1,038,265)	$ 757,466

Non-current Assets Held for Sale and Discontinued Operations - Assets, Liabilities and Equity of Disposal Group Classified as Held for Sale (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 TWD ($)
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Cash and cash equivalents	$ 8,035,714	$ 271,110	$ 7,571,366
Accounts receivable	4,015,734	135,484	4,140,246
Other receivables	56,716	1,914	57,411
Inventories	1,929,239	65,089	1,877,982
Other current financial assets			1,600
Property, plant and equipment, net	15,265,311	515,024	13,497,218	$ 455,372	$ 14,211,560
Refundable deposits	21,342	720	21,321
Other non-current assets	35,474	1,197	181,692
Assets of disposal group classified as non-current assets for sale			3,105,071
Accounts payable	687,960	23,210	825,062
Other payables	1,980,182	66,808	1,412,054
Receipts in advance	5,209	176	1,324
Bank loans - current portion	2,143,168	72,307	1,062,285
Lease payable - current	11,785	398	11,291
Other current liabilities	31,275	1,055	43,676
Bank loans - non-current	7,498,853	252,998	9,687,720
Lease payable - non-current	18,057	609	29,311
Long-term deferred revenue	24,898	840
Guarantee deposits	$ 1,371	$ 46	1,404
Liabilities of disposal group classified as liabilities directly related to non-current assets held for sale			587,639
Foreign currency translation reserve			287,645
Non-current assets held for sale [member]
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Cash and cash equivalents			389,897
Accounts receivable			230,523
Other receivables			202,909
Inventories			136,842
Prepayments			15,943
Other current financial assets			1,193
Property, plant and equipment, net			2,033,968
Refundable deposits			113
Prepaid rent - non-current portion			82,291
Other non-current assets			11,392
Accounts payable			98,973
Other payables			177,178
Receipts in advance			6,687
Bank loans - current portion			7,614
Lease payable - current			27,702
Other current liabilities			34,276
Bank loans - non-current			106,461
Lease payable - non-current			27,702
Long-term deferred revenue			100,395
Guarantee deposits			$ 651

Non-current Assets Held for Sale and Discontinued Operations - Results of Discontinued Operations (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Revenue	$ 17,940,855	$ 605,292	$ 18,387,593	$ 18,837,089
Cost of revenue	(14,703,729)	(496,077)	(14,745,472)	(14,685,514)
Other operating income (expenses), net	692,834	23,375	90,306	105,051
Profit (loss) from discontinued operations	1,814,953	61,233	(122,105)	(34,233)
Income tax expense	0	0	0	0
Loss from discontinued operations after income tax	(28,281)	(954)	(122,105)	(34,233)
Gain on disposal of discontinued operations	1,843,234	62,187
Profit (loss) from discontinued operations	1,814,953	61,233	(122,105)	(34,233)
Discontinued operations: ChipMOS Shanghai [member]
Noncurrent assets or disposal groups classified as held for sale or as held for distribution to owners [Line Items]
Revenue	227,095	7,662	1,005,166	1,032,302
Cost of revenue	(195,078)	(6,582)	(986,004)	(1,050,075)
Operating expenses	(58,840)	(1,985)	(179,178)	(51,910)
Other operating income (expenses), net	1,429	48	13,753	8,469
Non-operating income (expenses), net	(2,887)	(97)	24,158	26,981
Profit (loss) from discontinued operations	(28,281)	(954)	(122,105)	(34,233)
Profit (loss) from discontinued operations	$ 1,814,953	$ 61,233	$ (122,105)	$ (34,233)

Issued Capital - Summary of Issued Capital (Detail) shares in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 TWD ($) shares	Dec. 31, 2015 TWD ($) shares
Disclosure of classes of share capital [abstract]
Authorized shares, Ordinary shares	970,000	970,000	1,450,000	970,000
Ordinary shares	886,297	886,297	886,966	896,206
Issued capital	$ 8,862,971	$ 299,021	$ 8,869,663	$ 8,962,066

Issued Capital - Additional Information (Detail) - TWD ($)			12 Months Ended
	Oct. 31, 2016	Jun. 17, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	May 12, 2016	Feb. 04, 2016	Aug. 10, 2015	Dec. 31, 2014
Disclosure of classes of share capital [line items]
Ordinary shares par value				$ 10
Number of shares issued in order to exchange for the shares of ThaiLin		35,932,000
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Number of shares issued in order to exchange for the shares of ThaiLin		35,932,000	35,932,000
Maximum value of shares approved for repurchase						$ 600,000,000	$ 600,000,000	$ 826,800,000
Number of shares repurchased, retired and cancelled under share repurchase program			20,000,000
Number of shares repurchased under share repurchase program				30,000,000	30,000,000
Number of shares issued			896,206,000	886,297,000	886,966,000				864,619,000
Number of shares represented by each unit of ADS	20
Number of shares outstanding				188,630,000
American depositary share (each representing 20 common shares) [member]
Disclosure of classes of share capital [line items]
Number of shares issued	25,620,267
Number of shares represented by each unit of ADS	20
Number of shares outstanding				9,431,486

Issued Capital - Movement of Ordinary Shares Issued (Detail) pure in Thousands			12 Months Ended
	Oct. 31, 2016 shares	Jun. 17, 2015 shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares
Disclosure of classes of share capital [line items]
Transactions with non-controlling interests (Note 28)		35,932,000
Cancellation of ordinary shares from capital reorganization (Note 29)	(522,080,000)
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Beginning balance			886,966,000	896,206,000	864,619,000
Transactions with non-controlling interests (Note 28)		35,932,000			35,932,000
Restricted shares				435	15,752
Unearned restricted shares - cancelled			(669)		(97)
Share cancellation					(20,000,000)
Issuance of ordinary shares for capital reorganization (Note 29)	512,405,000			512,405,000
Cancellation of ordinary shares from capital reorganization (Note 29)				(522,080,000)
Ending balance			886,297,000	886,966,000	896,206,000

Capital Surplus and Retained Earnings - Details of Capital Surplus (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of reserves within equity [abstract]
Share premium	$ 5,873,743	$ 198,169	$ 6,473,471	$ 2,501,767
Share-based payment				849,482
Restricted shares	390,401	13,171	408,051	397,296
Others	7,304	247	7,304	7,304
Capital surplus	$ 6,271,448	$ 211,587	$ 6,888,826	$ 3,755,849

Capital Surplus and Retained Earnings - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure of reserves within equity [abstract]
Maximum percentage of capital surplus to paid-in-capital required by the ROC Securities and Exchange Act	10.00%
Percentage of income transferred to legal reserve	10.00%
Threshold percentage over capital stock to be distributed out of legal reserve	25.00%

Capital Surplus and Retained Earnings - Details of Retained Earnings (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of reserves within equity [abstract]
Legal reserve	$ 28,680	$ 223,047	$ 331,863
Cash dividend	257,026	$ 1,792,553	$ 1,999,225
Cash distribution from capital surplus	$ 599,728
Cash dividend, distribution per share	$ 0.30	$ 2.09	$ 2.22
Cash distribution from capital surplus	$ 0.70

Treasury Stock - Movement of Treasury Stock (Detail) shares in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 TWD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 TWD ($) shares
Beginning balance \| $	$ 1,007,654
Treasury stock (repurchased) \| $			$ 1,007,654		$ 1,862,362
Ending balance	$ 1,007,654	$ 33,997	$ 1,007,654
Treasury stock [member]
Treasury stock shares at beginning balance	30,085	30,085	0	0	0
Treasury stock shares (repurchased)			30,085	30,085	20,000
Treasury stock shares (cancelled)			0	0	(20,000)
Treasury stock shares at ending balance	30,085	30,085	30,085	30,085	0
Beginning balance	$ 1,007,654	$ 33,997	$ 0		$ 0
Treasury stock (repurchased)	0	0	1,007,654		633,737
Treasury stock (cancelled)	0	0			(633,737)
Ending balance	$ 1,007,654	$ 33,997	$ 1,007,654	$ 33,997	$ 0

Long-term Bank Loans - Summary of Long-term Bank Loans (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2017 USD ($)
Disclosure of detailed information about borrowings [Line Items]
Long-term bank loans	$ 9,642,021	$ 10,750,005	$ 325,305
Less: Current portion (fee included)	(2,143,168)	(1,062,285)	(72,307)
Syndicated bank loans, excluding current portion	7,498,853	9,687,720	252,998
Long-term bank loans [Member]
Disclosure of detailed information about borrowings [Line Items]
Unused credit lines of long-term bank loans	2,400,000	2,400,000	0
Gross carrying amount [member] \| Syndicated Bank Loans Repayable from December 2017 to June 2021 [Member]
Disclosure of detailed information about borrowings [Line Items]
Long-term bank loans	$ 9,675,301	$ 10,800,000	$ 326,427
Period and payment term	Borrowing period is from June 30, 2016 to June 30, 2021; interest is repayable monthly; principal is repayable semi-annually from December 30, 2017.	Borrowing period is from June 30, 2016 to June 30, 2021; interest is repayable monthly; principal is repayable semi-annually from December 30, 2017.
Interest rate range	1.7895%	1.7895%	1.7895%
Syndicated loan fee [Member]
Disclosure of detailed information about borrowings [Line Items]
Long-term bank loans	$ (33,280)	$ (49,995)	$ (1,122)

Long-term Bank Loans - Additional Information (Detail) $ in Billions	May 16, 2016 TWD ($) Bank
Disclosure of detailed information about borrowings [Line Items]
Number of banks in syndicate \| Bank	10
Syndicated loan [Member]
Disclosure of detailed information about borrowings [Line Items]
Principal amount of loan \| $	$ 13.2
Maturity of loan	Five years

Long-term Bank Loans - Details of Repayment Schedule in Respect of Bank Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 9,642,021	$ 325,305	$ 10,750,005
Within 1 year [member]
Disclosure of detailed information about borrowings [Line Items]
Bank loans	2,143,168	72,307	1,062,285
2-5 years [member]
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 7,498,853	$ 252,998	$ 9,687,720

Retirement Benefit Plans - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($) Years Unit	Dec. 31, 2017 USD ($) Years Unit	Dec. 31, 2016 TWD ($)
Disclosure of defined benefit plans [Line Items]
Defined benefit plans expected contribution	$ 26,910	$ 908
Weighted average duration of the defined benefit obligation \| Years	13.4	13.4
Defined benefit pension plan [Member]
Disclosure of defined benefit plans [Line Items]
Number of units accrued in first tranche	2	2
Duration of first tranche	First 15 years	First 15 years
Number of units accrued in second tranche	1	1
Duration of second tranche	Thereafter 15 years	Thereafter 15 years
Maximum number of units accruable under the pension plan	45	45
Benefit measurement period	6 months	6 months
Employer contribution percentage	2.00%	2.00%
Defined contribution pension plan [member]
Disclosure of defined benefit plans [Line Items]
Employer contribution percentage	6.00%	6.00%	6.00%
Pension costs under defined contribution pension plans	$ 190,106	$ 6,414	$ 174,096

Retirement Benefit Plans - Defined Benefit Plans Amounts Recognized in Statements of Financial Position (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 TWD ($)
Surplus (deficit) in plan [abstract]
Present value of defined benefit obligations	$ (838,543)	$ (28,291)	$ (894,163)
Fair value of plan assets	360,017	12,146	347,195
Net defined benefit liability	$ (478,526)	$ (16,145)	$ (546,968)	$ (18,454)	$ (519,471)

Retirement Benefit Plans - Movements in Net Defined Benefit Liability (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	$ (546,968)	$ (18,454)	$ (519,471)
Current service cost	(386)	(13)	(321)
Interest (expense) income	(8,010)	(270)	(8,876)
Total	(555,364)	(18,737)	(528,668)
Return of plan assets (not including the amount included in interest income or expense)	(1,842)	(62)	(3,413)
Financial assumption movement effect	28,506	962	(31,294)
Experience adjustments	24,174	815	(8,676)
Gain (loss) on remeasurement, net defined benefit liability (asset)	50,838	1,715	(43,383)
Pension fund contribution	26,000	877	25,083
Ending balance	(478,526)	$ (16,145)	(546,968)
Present Value of Defined Benefit Obligation [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	(894,163)		(844,166)
Current service cost	(386)		(321)
Interest (expense) income	(13,236)		(14,644)
Total	(907,785)		(859,131)
Financial assumption movement effect	28,506		(31,294)
Experience adjustments	24,174		(8,676)
Gain (loss) on remeasurement, net defined benefit liability (asset)	52,680		(39,970)
Paid pension	16,562		4,938
Ending balance	(838,543)		(894,163)
Fair Value of Plan Assets [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	347,195		324,695
Interest (expense) income	5,226		5,768
Total	352,421		330,463
Return of plan assets (not including the amount included in interest income or expense)	(1,842)		(3,413)
Gain (loss) on remeasurement, net defined benefit liability (asset)	(1,842)		(3,413)
Pension fund contribution	26,000		25,083
Paid pension	(16,562)		(4,938)
Ending balance	$ 360,017		$ 347,195

Retirement Benefit Plans - Principal Actuarial Assumptions Used and Sensitivity Analysis of Present Value of Defined Benefit Obligation Effected by Changes of Principal Actuarial Assumptions (Detail)	Dec. 31, 2017	Dec. 31, 2016
Disclosure of sensitivity analysis for actuarial assumptions [abstract]
Discount rate used in determining present values	1.75%	1.50%
Expected future salary increases	3.50%	3.50%

Retirement Benefit Plans - Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Actuarial assumption of discount rates [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ (27,192)	$ (31,294)
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ 28,506	$ 32,893
Actuarial assumption of expected rates of salary increases [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ 27,955	$ 32,174
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ (26,816)	$ (30,787)

Retirement benefit plans - Analysis of Timing of the Future Pension Payment (Detail) - Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 341,132	$ 11,509
Within 1 year [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	28,007	945
1-2 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	31,702	1,070
2-5 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	102,703	3,465
6-10 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 178,720	$ 6,029

Other Payables - Summary of Other Payables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Trade and other current payables [abstract]
Salaries and bonus payable	$ 601,239	$ 20,285	$ 443,993
Interest payable	2,854	96	1,059
Accrued pension costs	32,402	1,093	29,930
Employees' bonus	371,912	12,548	70,553
Directors' remuneration	18,596	627	3,528
Other expense payable	953,179	32,159	862,991
Other payables	$ 1,980,182	$ 66,808	$ 1,412,054

Provisions - Current - Movements in Provisions (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of other provisions [Line Items]
Beginning balance	$ 80,719	$ 2,723
Provision	236,552	7,981
Payment	(189,960)	(6,409)
Ending balance	127,311	$ 4,295
Provisions for sales allowance [member]
Disclosure of other provisions [Line Items]
Beginning balance	66,065
Provision	117,234
Payment	(113,143)
Ending balance	70,156
Provisions for deficiency compensation [member]
Disclosure of other provisions [Line Items]
Beginning balance	14,654
Provision	119,318
Payment	(76,817)
Ending balance	$ 57,155

Short-term Bank Loans - Summary of Short-term Bank Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)
Disclosure of detailed information about borrowings [Line Items]
Unsecured bank loans	$ 969,353	$ 32,704
Bottom of range [member]
Disclosure of detailed information about borrowings [Line Items]
Annual interest rate	0.55%	0.55%
Top of range [member]
Disclosure of detailed information about borrowings [Line Items]
Annual interest rate	1.71%	1.71%

Short-term Bank Loans - Unused Credit Lines of Short-term Bank Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2016 USD ($)
Short-term bank loans [member]
Disclosure of detailed information about borrowings [Line Items]
Unused credit lines of short-term bank loans	$ 3,028,357	$ 80,000	$ 3,119,000	$ 80,000

Significant Commitments and Contingencies - Future Minimum Lease Payments under Operating Lease Contracts (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure of finance lease and operating lease by lessee [Line Items]
Minimum finance lease payments payable	$ 309,423	$ 10,439	$ 357,154
Within 1 year [member]
Disclosure of finance lease and operating lease by lessee [Line Items]
Minimum finance lease payments payable	39,342	1,327	39,929
2-5 years [member]
Disclosure of finance lease and operating lease by lessee [Line Items]
Minimum finance lease payments payable	130,182	4,392	140,328
More Than 5 Years [member]
Disclosure of finance lease and operating lease by lessee [Line Items]
Minimum finance lease payments payable	$ 139,899	$ 4,720	$ 176,897

Significant Commitments and Contingencies - Additional Information (Detail) $ in Thousands, $ in Thousands		12 Months Ended
	Oct. 31, 2016 TWD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015
Capital commitments [abstract]
Amount guaranteed by Bank of Taiwan		$ 131,000	$ 97,500	$ 3,289
Reduction of unappropriated retained earnings through capital transfer	$ (5,052,343)	$ (5,052,343)
Unappropriated retained earnings percentage		10.00%			10.00%

Transactions with Non-controlling Interests - Additional Information (Detail) $ / shares in Units, shares in Thousands, $ in Thousands			12 Months Ended
	Jun. 17, 2015 TWD ($) $ / shares shares	Jun. 16, 2015	Dec. 31, 2015 TWD ($)
Disclosure of noncontrolling interests [Line Items]
Merger, cash offered for shareholders \| $ / shares	$ 12.5
Merger, ratio of ordinary share exchange for each share held	0.311
Merger, number of shares issued by surviving company \| shares	35,932
Merger, cash paid by surviving company to exchange for shares \| $	$ 1,444,224		$ 1,444,224
Merger, percentage of shares exchanged	52.46%
ThaiLin Semiconductor Corp. [member]
Disclosure of noncontrolling interests [Line Items]
Merger, percentage of voting share held		47.54%
ChipMOS TECHNOLOGIES (BVI) LTD. [member]
Disclosure of noncontrolling interests [Line Items]
Percentage of ownership on outstanding shares		100.00%
ChipMOS TECHNOLOGIES (Shanghai) LTD. [member]
Disclosure of noncontrolling interests [Line Items]
Percentage of ownership on outstanding shares		100.00%

Transactions With Non-controlling Interests - Summary of Effect on Equity Attributed to the Company from Transactions with Non-controlling Interests (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015 TWD ($)
Effect on the equity	$ (1,444,224)
Non-controlling interests [member]
Effect on the equity	(2,637,316)
Capital surplus [member]
Effect on the equity	1,091,305
ThaiLin Semiconductor Corp. [member] \| Non-controlling interests [member]
Effect on the equity	2,637,316
Consideration paid to non-controlling interests	(2,921,041)
ThaiLin Semiconductor Corp. [member] \| Foreign currency translation reserve [member]
Effect on the equity	(17,964)
ThaiLin Semiconductor Corp. [member] \| Capital surplus [member]
Effect on the equity	26,189
ThaiLin Semiconductor Corp. [member] \| Unappropriated retained earnings [member]
Effect on the equity	$ (275,500)

Capital Reorganization - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands		12 Months Ended
	Oct. 31, 2016 TWD ($) $ / shares shares	Dec. 31, 2016 TWD ($) shares	Dec. 31, 2017 shares	Oct. 31, 2016 USD ($) shares	Oct. 30, 2016 TWD ($)	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Disclosure of capital reorganization [Line Items]
Cash per share the former parent is entitles to receive under the Merger Agreement \| $ / shares	$ 3.71
Total consideration paid	$ 3,208,310	$ 3,208,310		$ 101,657
Directly attributable transaction cost \| $	133,311	133,311
Cash for capital reorganization \| $	$ 3,341,621	3,341,621
Number of shares cancelled	522,080,000
Reduction of unappropriated retained earnings through capital transfer \| $	$ (5,052,343)	$ (5,052,343)
Decrease in number of shares	(9,675,000)
Equity attributable to predecessors' interests \| $					$ 1,692,918
American depositary share (each representing 20 common shares) [member]
Disclosure of capital reorganization [Line Items]
Number of units of ADS the former parent is entitled to receive under the Merger Agreement \| $ / shares	$ 0.9355
Number of shares represented by each unit of ADS	20
Number of shares issued	25,620,267			25,620,267
Ordinary shares [member]
Disclosure of capital reorganization [Line Items]
Number of shares represented by each unit of ADS	20
Number of shares issued		886,966,000	886,297,000			896,206,000	864,619,000
Issuance of ordinary shares for capital reorganization	512,405,000	512,405,000
Number of shares cancelled		522,080,000

Supplementary Cash Flow Information - Partial Cash Paid for Investing and Financing Activities (Detail) $ in Thousands, $ in Thousands		12 Months Ended
	Oct. 31, 2016 TWD ($)	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)	Dec. 31, 2017 USD ($)	Oct. 31, 2016 USD ($)
Statement of cash flows [abstract]
Purchase in property, plant and equipment		$ 4,849,331	$ 163,608	$ 4,690,995	$ 3,644,560
Add: Beginning balance of payable to contractors and equipment suppliers		839,983	28,339	523,962	1,307,459
Add: Beginning balance of lease payable		94,952	3,204
Less: Ending balance of payable to contractors and equipment suppliers		(878,065)	(29,624)	(647,486)	(523,962)
Less: Ending balance of lease payable		(84,192)	(2,841)	(96,006)
Less: Transfer from prepaid equipment (shown as "Other non-current assets")		(139,304)	(4,700)
Cash paid for acquisition of property, plant and equipment		4,682,705	157,986	4,471,465	4,428,057
Repurchase of shares				1,007,654	1,862,362
Less: Beginning balance of prepayment for the repurchase of shares					(421,003)
Cash paid for purchase of treasury stock				1,007,654	$ 1,441,359
Net assets acquired from ChipMOS Bermuda				12,987,736
Less: Issuance of shares				(9,779,426)
Cash consideration	$ 3,208,310			3,208,310			$ 101,657
Directly attributable transaction cost	133,311			133,311
Cash paid for capital reorganization	$ 3,341,621			$ 3,341,621
Disposal of a subsidiary		2,166,151	73,082
Add: Ending balance of other payables		64,393				$ 2,173
Less: Cash and cash equivalents of discontinued operations		(449,331)				$ (15,160)
Cash received from disposal of a subsidiary		$ 1,781,213	$ 60,095

Supplementary Cash Flow Information - Partial Cash Paid for Investing and Financing Activities (Parenthetical) (Detail) - Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of supplementary cash flow information [line items]
Ending balance of other payables will be payable in 2018	$ (64,393)	$ (2,173)
ChipMOS Shanghai [member]
Disclosure of supplementary cash flow information [line items]
Ending balance of other payables will be payable in 2018	$ 64,393	$ 2,173

Supplementary Cash Flow Information - Reconciliation of Liabilities Arising from Financing Activities (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	$ 10,751,409
Cash flow	(155,379)
Non-Cash flow, Amortization of loans fee	16,715
Ending balance	10,612,745	$ 358,055
Long-term loans (include the current portion) [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	10,750,005
Cash flow	(1,124,699)
Non-Cash flow, Amortization of loans fee	16,715
Ending balance	9,642,021	325,305
Short-term loans [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Cash flow	969,353
Ending balance	969,353	32,704
Guarantee deposits [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	1,404
Cash flow	(33)
Ending balance	$ 1,371	$ 46

Supplementary Cash Flow Information - Reconciliation of Liabilities Arising from Financing Activities (Parenthetical) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Proceeds from long-term bank loans	$ 148,829	$ 5,021	$ 10,560,000	$ 2,000,000
Proceeds from short-term bank loans	5,560,354	187,596	$ 3,820,594	$ 4,725,030
Discontinued operations: ChipMOS Shanghai [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Proceeds from long-term bank loans	148,829	5,021
Proceeds from short-term bank loans	$ 312,483	$ 10,543

Related Party Transactions - Additional Information (Detail) ¥ in Thousands, $ in Thousands	1 Months Ended					9 Months Ended		12 Months Ended
	Jun. 30, 2017 TWD ($)	Jun. 30, 2017 USD ($)	Jan. 31, 2017 USD ($)	May 31, 2016 USD ($)	Oct. 31, 2011 CNY (¥) Installments	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)	Dec. 31, 2017 USD ($)
Disclosure of transactions between related parties [Line Items]
Disposal of property, plant and equipment								$ 34,233,000	$ 1,155
Acquisition of investment in associate								1,373,486,000	46,339		$ 116,000,000
Long-term deferred revenue						$ 24,898,000		24,898,000				$ 840
Royalty income								$ 11,998,000	$ 405
ChipMOS Shanghai patent licensing agreement [member]
Disclosure of transactions between related parties [Line Items]
Licensing fee			$ 1,000	$ 2,500
License agreement term								10 years	10 years
Percentage of licensed products revenue								0.50%	0.50%
Receipts in advance						3,018,000		$ 3,018,000				102
Long-term deferred revenue						24,898,000		24,898,000				840
Royalty income						2,828,000	$ 96
ChipMOS Shanghai and bermuda patent licensing agreement [Member]
Disclosure of transactions between related parties [Line Items]
Licensing fee \| ¥					¥ 27,400
License agreement term					10 years
Receipts in advance						$ 1,039,000		1,039,000				$ 35
Royalty income								$ 9,170,000	$ 309
Number of quarterly installments \| Installments					40
Quarterly installment amount \| ¥					¥ 685
ChipMOS Shanghai [member]
Disclosure of transactions between related parties [Line Items]
Disposal of property, plant and equipment										$ 0	0
JMC ELECTRONICS CO., LTD. [member]
Disclosure of transactions between related parties [Line Items]
Disposal of property, plant and equipment										0	0
ChipMOS Shanghai [member]
Disclosure of transactions between related parties [Line Items]
Relationship								Associate	Associate
ChipMOS Shanghai								$ 41,183,000	$ 1,389	0	0
Acquisition of investment in associate	$ 1,373,486,000	$ 46,339
JMC ELECTRONICS CO., LTD. [member]
Disclosure of transactions between related parties [Line Items]
Relationship								Associate	Associate
ChipMOS Shanghai										$ 0	$ 0

Related Party Transactions - Summary of Significant Related Party Transactions (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of transactions between related parties [Line Items]
Selling price	$ 306,634	$ 10,345	$ 59,134	$ 48,275
Gain on disposal	132,777	4,480	$ 2,575	$ 1,562
ChipMOS Shanghai [member]
Disclosure of transactions between related parties [Line Items]
Selling price	21,982	742
Gain on disposal	$ 20,240	$ 683

Related Party Transactions - Key Management Personnel Compensation (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)	Dec. 31, 2015 TWD ($)
Disclosure of transactions between related parties [abstract]
Short-term employee benefits	$ 188,105	$ 6,346	$ 152,319	$ 217,091
Post-employment compensation	5,622	190	3,335	2,249
Share-based payments	18,736	632	109,255	100,280
Key management personnel compensation	$ 212,463	$ 7,168	$ 264,909	$ 319,620

Pledged or Mortgaged Assets - Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Disclosure assets pledged as collateral [abstract]
Property, plant and equipment, net	$ 7,164,089	$ 241,703	$ 8,020,905
Other financial assets - non current	70,241	2,370	70,677
Assets pledged as collateral for liabilities	$ 7,234,330	$ 244,073	$ 8,091,582

Financial Instruments by Category - Summary of Financial Instruments by Category (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 TWD ($)
Financial assets
Available-for-sale financial assets	$ 20,890	$ 705	$ 9,960
Loans and receivables (including cash and cash equivalents, other financial assets, accounts and notes receivable, other receivables and refundable deposits)	12,204,292	411,751	11,862,621
Financial assets	12,225,182	412,456	11,872,581
Financial liabilities
Financial liabilities at amortized cost (including bank loans, accounts payable, payables to contractors and equipment suppliers, lease payable, other payables and guarantee deposits)	$ 14,024,304	$ 473,155	$ 13,579,473

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

Financial Risk Management and Fair Values of Financial Instruments - Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations (Detail) ¥ in Thousands, ¥ in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2017 TWD ($) $ / $ $ / JPY $ / CNY	Dec. 31, 2017 USD ($) $ / $ $ / JPY $ / CNY	Dec. 31, 2017 JPY (¥) $ / $ $ / JPY $ / CNY	Dec. 31, 2017 CNY (¥) $ / $ $ / JPY $ / CNY	Dec. 29, 2017 $ / $	Dec. 31, 2016 TWD ($) $ / $ $ / JPY	Dec. 31, 2016 USD ($) $ / $ $ / JPY	Dec. 31, 2016 JPY (¥) $ / $ $ / JPY
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate					29.64
Assets denominated in foreign currencies	$ 12,225,182	$ 412,456				$ 11,872,581
Currency Risk [member] \| US$ [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	29.7600	29.7600	29.7600	29.7600		32.2500	32.2500	32.2500
Assets denominated in foreign currencies	$ 6,192,044	$ 208,066				$ 5,746,982	$ 178,201
Liabilities denominated in foreign currencies	$ 477,231	$ 16,036				$ 251,615	$ 7,802
Currency Risk [member] \| JPY [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate \| $ / JPY	0.2642	0.2642	0.2642	0.2642		0.2756	0.2756	0.2756
Assets denominated in foreign currencies	$ 210,899		¥ 798,254			$ 142,517		¥ 517,114
Liabilities denominated in foreign currencies	$ 283,072		¥ 1,071,432			$ 151,706		¥ 550,456
Currency Risk [member] \| RMB [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate \| $ / CNY	4.5650	4.5650	4.5650	4.5650
Assets denominated in foreign currencies	$ 764,564			¥ 167,484

The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to deliver a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]